Seahorse Breeding Secrets

Seahorse Breeding Secrets: Ten Common Mistakes and How to Avoid Them

by Pete Giwojna – from the January 1999 issue of Freshwater and Marine Aquarium magazine (FAMA)

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Seahorses breed more readily in the aquarium than any other marine fishes. Males and females are easy to sex, form permanent pair bonds, and breed continuously throughout the year in captivity, often re-mating scant hours after their latest brood has been delivered. With the exception of their feeding regimen, their aquarium requirements are fairly undemanding, and as bay fishes, they tolerate fluctuations in salinity and temperature and water conditions that would quickly prove fatal for most other exotic fish.

All of which has led some aquarists to conclude that successfully breeding seahorses is simply a matter of introducing a mature male and female in an aquarium of their own, providing them with good water quality and plenty of nutritious live foods, and letting nature take its course.

But it’s rarely that easy. When it comes to breeding seahorses, the path to success is booby-trapped with a myriad of well-disguised pitfalls which can engulf the unsuspecting aquarist at any step along the way. Many hidden factors affect seahorses reproduction, and neglecting any one of them can doom your breeding efforts to failure. To make matters worse, these factors are often seemingly unimportant details and minor considerations that even the most experienced aquarists can easily overlook.

Over the years, I have received many letters and phone calls from puzzled aquarists and frustrated hobbyists wondering why, for no apparent reason, their seahorses fail to pair up or refuse to reproduce. Analyzing these problems has been very instructive. In most cases, the problem proved to be some insignificant detail or trifling concern which the hapless hobbyist simply never realized might present a difficulty. For example, the dimensions of the breeding tank, the sort of equipment you chose and the way it’s installed, the type of aeration and lighting you provide, and even the way the aquarium is decorated can all make a crucial difference.

Thus, in this article, we will discuss the ten most common mistakes seahorse breeders make and how to avoid these pitfalls. Fortunately, as you will see, once such potential problems have been identified, they are easily prevented or corrected.

Mistake No. 1 – Poorly-Conditioned Brood Stock:

The first goal of every serious seahorse breeder is to obtain healthy, well-conditioned brood stock. This is an obvious point and hobbyists seldom err in that regard due to a lack of awareness. Rather, the problem here is that good brood stock can often be difficult to find.

Solution: The best way to obtain healthy seahorses at the peak of their stamina and vigor is to collect them yourself or to order them directly from the collector. (Ideally, one could obtain tank-raised seahorses that have been bred and reared in the aquarium for several generations to serve as brood stock. Such specimens would already be accustomed to eating aquarium fare and well-adjusted to aquarium life. At this point, however, tank-raised seahorses are rarely available, with the possible exception of Hippocampus zosterae, the pygmy pony.) But the sad fact is that collecting one’s own specimens or purchasing tank-raised stock is simply not an option for the vast majority of hobbyists.

For all practical purposes, most of us will have to make do with the specimens stocked by our local fish stores. The key to success here is to select freshly-collected seahorses at the peak of health that are still in their prime.

By the time they finally arrive at your local dealers, seahorses may already have spent a long time in the collector’s holding tanks followed by an indefinite stay at a wholesaler. Due to their need for live foods, they are very likely to have gone unfed during this entire period, and they may have become malnourished by the time they reach your neighborhood fish store.

To minimize this problem, try to find out when your dealer is expecting his next shipment of seahorses and then select your breeders as soon as they arrive. Look for a mature male and female of similar size–the bigger the better–and avoid any specimens with obvious signs of disease.

Check for starvation by observing the seahorses head-on: a well-fed seahorse should be somewhat rotund or convex in cross-section, while a malnourished specimen will have a sunken, concave appearance. A seahorse that is obviously gaunt and emaciated must be passed over.

I’ve learned this lesson the hard way. On several occasions, I’ve attempted to rescue starving seahorses from pet shops, convinced that if I could only get them home to my reef tank, they were bound to regain their health. My mini reef is designed specifically for Hippocampids, and I felt sure I could restore them to peak condition by providing them with natural surroundings, optimum water quality, and all of their favorite live foods they could eat.

Sadly, that was rarely the case. It appears that once the starvation has progressed beyond a certain point, it is irreversible; at some stage in the process, the fish will begin to consume its own tissues, and once the digestive tract becomes involved in this process, the fish can literally no longer eat.

When that happens, the half-starved seahorse will either totally ignore any and all offerings or eagerly approach the food items, track them intently, and close rapidly to within easy striking distance, only to turn away at the last instant. Despite being tempted with their favorite morsels and displaying every indication of a ravenous appetite, the starved ‘horses seem incapable of ”pulling the trigger” on their intended prey. They will eagerly go through all the motions of eating, only to have the feeding process break down in the final step at the moment of truth. Nothing is quite so disheartening as having to sit by and watch helplessly as a seahorse slowly dwindles away while surrounded by luscious live foods and tempting tidbits, literally starving itself to death in the midst of plenty. Needless to say, it’s best to leave any seahorses that may be suffering from starvation syndrome in the dealer’s tank.

Aside from avoiding specimens that are little more than swimming skeletons, the first things to look for when picking out seahorses are obvious signs of disease such as tattered fins, fungus, or external parasites. Seahorses that have been housed with fin-nipping fishes or collected in trawls often suffer severe fin damage. Ordinarily, this is not a serious condition. Seahorses have amazing regenerative abilities, and even specimens whose fins have been nipped, eaten, or torn away entirely will usually regrow them completely within a week or two (Giwojna, 1990). But there’s always a chance that secondary infections will develop at the site of the injury or that the damage could be due to fin rot, so it’s best not to take a chance on a seahorse with ragged, limp fins.

Fungus can also be a common problem, particularly late in the season. Seahorses often develop patches of fungus on their bodies after they have been chilled, which can easily happen with specimens that are collected or shipped in the late fall and winter. Localized fungus problems associated with an injury can develop at any time of year. It will appear as a fuzzy, cotton-like growth at the sight of the wound, and seahorses afflicted with either type of fungus should not be considered as brood stock.

In addition, beware of sea lice and external parasites when selecting your breeders. Freshly-collected seahorses are frequently infested with a nasty little blood-sucking parasite known as the sea louse (Argulus sp.), but careful examination of the ‘horse’s head and the nape of its neck–the little beasty’s favorite hiding places–will quickly reveal their unwelcome presence. Sea lice have small, flattened bodies and assume the same coloration as their host, so a good eye and close observation are necessary to detect them[1]. They will appear as small, semi-transparent bumps on their host, and can easily be manually removed with a tweezers (Giwojna, 1990). Argulus range in size from pinpoint-sized babies to quarter-inch adults, and a heavily infested seahorse can become badly debilitated from loss of blood and may become so irritated and tormented by these vampires that it loses all interest in eating, let alone breeding. Although they are not usually a serious problem, sea lice are just another complication the aquarist doesn’t need to deal with when attempting to breed seahorses, so badly infested specimens should be quickly rejected.

Some external parasites may not be revealed by a visual inspection. For example, the white spots characteristic of Oodinium and Cryptocaryon are only evident when those diseases have progressed to a dangerously advanced stage. However, the seahorse’s behavior will usually reveal the presence of such parasites. Crypt and Oodinium attack the gills first and affect the fish’s breathing, so the first symptom is usually rapid respiration. Avoid any seahorses with labored breathing or that attempt to scratch themselves against the coral or gravel.

Once you’ve eliminated those specimens with obvious signs of disease and settled on a pair of likely-looking seahorses, there is one last test they must pass before you bring your breeders home. Ask the dealer to feed them. Most dealers will be happy to accommodate you in the interest of making a sale, and if the dealer keeps seahorses in stock but does not have live foods or a suitable substitute on hand to feed them, it would be better to purchase your stock elsewhere since the seahorses are not receiving adequate care. Ordinarily, these natural-born gluttons are always hungry, so there is something seriously wrong with a seahorse that shows no interest in live foods.

The brood stock you select should be alert, as indicated by busy eyes intently scanning their surroundings, have a healthy appetite, and display an active interest in food. Obtaining healthy, well-conditioned brood stock is a vital first step for anyone who hopes to breed these fascinating fish, but once that’s accomplished, half the battle has been won.

Mistake No. 2 – Overcrowding:

Seahorses are relatively inactive, nonaggressive fishes, and aquarists are often tempted to take advantage of the fact that several of them will coexist peacefully together. Many hobbyists feel that a herd of ‘horses makes a more attractive display than a pair or a single specimen; others keep them in groups in the hope that this will facilitate breeding. In the latter case, this is often done in the mistaken belief that the ”herd” is the seahorse’s natural social group, since they exist in ”colonies” in the wild, and providing them with a selection of prospective partners to choose from will therefore allow them to find suitable mates and form compatible pairs more easily.

In actuality, seahorses are solitary animals that rarely interact with others of their kind outside of their mates. They have a distribution pattern in their natural habitat that can best be described as patchy. A large colony of a small, prolific species such as Hippocampus whitei may consist of several dozen individuals scattered across a grass flat covering many hundreds of square meters (Vincent and Sadler, 1995). With the exception of their mates, members of the ”colony” rarely encounter one another and when they do, as a rule, they refuse to interact.

The normal social group of the seahorse is the mated pair. Nearly all species that have studied in the laboratory or the field haven proven to be monogamous. Once a pair bond is established, the male will adopt a small home base within his mate’s much larger territory[2], seldom straying from that tiny section of seagrass thereafter. For instance, the male Hippocampus whitei operates from a home base of perhaps one square meter, while his mate’s territory is often up to 100 square meters–one hundred times greater (Vincent and Sadler, 1995). Consequently, studies show that day after day, paired males can be found in the same spot on the vast grass flats. This arrangement allows the male and female to live together and have daily contact with each other without competing for food, but it also means that mated pairs seldom come in contact with other seahorses. Ordinarily, the only other seahorses they meet are widowed or otherwise unpaired males in search of an available female, and these roaming bachelors are universally ignored or rebuffed by established pairs (Vincent, 1990).

Consequently, when so much as a trio of unpaired seahorses are confined together in an aquarium, chaos and confusion can result as two rivals compete for the same mate. This is because seahorses engage in an elaborate three-day courtship ritual prior to mating in order to ensure that a receptive male will be available after the female has ripened her eggs. This prolonged courtship proceeds in distinct stages as the prospective partners perform specific moves and counter-moves, and it can easily be disrupted at any point in the process by the type of competition that results when a third seahorse is present. This is potentially disastrous because mating is the climax of the courtship ritual and will not take place until the courtship has been successfully completed.

What do I mean by chaos and confusion? I’m talking about normally passive, totally nonaggressive fish suddenly engaging in no-holds barred wrestling matches and exchanging sucker punches and knock-out blows. I’m talking spousal abuse, with hapless females taking a beating when they get trapped in the middle of a melee between two rival males. I’m talking about shameless home-wreckers trying everything from lies, trickery, and deception to brute force in order to come between would-be mates. As for confusion, crowded conditions often result in homosexual mating attempts, with over-aroused males trying to copulate with other stallions and frustrated females rising to mate with other fillies (Vincent, 1990)!

In its mildest form, this sort of competition begins when the odd-man out in a trio of unpaired seahorses attempts to interfere with the other couple by interposing its body between them, as if ”cutting in” on their courtship dance (Vincent, 1990). If this simple ploy fails to break up the budding romance, the intruder may then decide to take matters into his own hands by wrapping his tail around his rival and actively restraining him. If the opponents are evenly matched, a strenuous wrestling match will ensue, with each adversary trying its best to forcibly remove the other from the female’s presence. If neither rival can overpower the other and gain the upper hand, the competition can quickly escalate until the males come to actual blows.

When that happens, a male will incline his head towards his rival and point his tubular snout directly at him, lining up his victim in his sights exactly as if staring down the barrel of a rifle. Once satisfied with his aim, the male will cock his head downwards and pull the trigger, delivering a sharp blow with a powerful upwards ”snap” of its snout. Knocked reeling, the recipient of the blow will keel over backwards from its pivot point and slowly right itself again, usually launching a counter-attack of its own on the upswing. The over-stimulated stallions will then trade punches back and forth until one of them delivers a decisive blow. This typically takes the form of a well-directed snap to the opponent’s operculum. (The operculum or gill cover is the Achille’s heel of the seahorse–a soft spot or chink in its suit of armor.) A sharp blow to this sensitive spot can knock a rival careening over a distance of several inches, and usually results in an immediate KO (Vincent, 1990).

Short of a knock-out punch, this sort of sparring only serves to get the competitors all the more excited, which can be rough on the nearby female, who, of course, is the object of the entire exercise in the first place. Overzealous males sometimes swim right over the female, trampling her underfoot in their haste to get at their adversary, and woe to the luckless lady who gets caught in the crossfire between two sparring males (Vincent, 1990). She will certainly be snapped at inadvertently, and may even find herself stuck smack dab in the middle of a tail-wrestling tug-o-war, pulled in opposite directions by her admirers–the same sort of rough treatment Olive Oyl so often received from Popeye and Bluto in the cartoons.

In self-defense, the harassed female often attempts to evade sparring males by darkening and flattening herself against the bottom in submission, or by swimming to the top and suspending high in the water column in order to escape the notice of her pumped-up paramours, since courtship and competition take place on the bottom and seahorses seldom look upwards. But in the close confines of the aquarium, it is impossible for a female to escape the attention of her over-sexed suitors for long, and even submissive females sometimes get dragged around the tank by rival males in the heat of combat.

As heated as this sort of intra-specific competition may become between seahorses of the same species, interspecific competition between different breeds of seahorses is likely to be worse (C.E. Keen, personal communication). For example, Carol Keen reports a violent confrontation between a male reidi and a newly introduced male of a different species which eventually had to be separated for the sake of the newcomer. The reidi brightened, charged up to the ‘intruder’ and wrapped his tail around the newcomers neck, pinning the hapless male to the bottom. The reidi maintained its stranglehold while it flashed through a series of intimidating color changes, its adversary signaling its distress all the while by becoming progressively paler until it was nearly white. When it became obvious that the reidi was not about to relinquish its grip, Keen was forced to break up the brawl and rescue the blanched male. (Ironically, the mauled male had been purchased as an interim companion for the reidi, which hadn’t been its old self since losing its mate. In a way, the operation was a success–the reidi male certainly perked up right away, and went on to pair up and produce a new brood with a replacement female.)

It appears interspecific competition poses a greater risk to the combatants than the ritualistic duels between members of the same species. When the competition is between different species, the opponents may be unable to recognize each other’s displays of aggression or submission signals. Confrontations can thus quickly escalate in violence, and the submissive seahorse may not be allowed to cry ”Uncle!” and yield before harm has been done. In such situations, as Keen remarked, it’s like the seahorses don’t even speak the same language[3].

Worst of all, under crowded conditions, seahorses sometimes attempt to mate with members of the same sex. These homosexual copulations are usually the result of confusion (Vincent, 1990). For example, sometimes a male and female will rise together as usual–the final phase of courtship leading to copulation–only to have a rival intrude at the crucial moment when the transfer of eggs is about to take place; just as the couple is about to merge in midwater, a rival will swim up and wedge itself between them, mistakenly resulting in a male-male (or female-to-female) mating attempt. Other times, a three-some will rise together, only to have the female fall back at the last moment, leaving two males to complete the copulatory rise.

On occasion, however, two over-stimulated stallions will persist in their futile attempts to pair with each other, as if oblivious to the sex of their ill-chosen partner. Fielder reported a case where two male Hippocampus hippocampus courted one another for over two hours and unsuccessfully attempted at least 20 copulatory rises together, despite the presence of a very frustrated female who actively intruded several times. Further, in her famous study on the reproductive ecology of seahorses, Amanda Vincent found that such male-male copulatory rises lasted fully as long as heterosexual mating attempts (Vincent, 1990). Successful breeding is clearly hindered by such unnatural behavior.

Female-female mating attempts are even more disastrous, since they often result in an overly-ripe female dropping her eggs. When that happens, the competition is all over, since a female that has lost her clutch has nothing to offer a prospective mate. In fact, some females are thought to use this as a ruse to deliberately eliminate their competition (Vincent, 1990). These cunning courtesans will entice a rival female to rise with them, and then hang back slightly beneath her, in a position to pose as a receptive male. If the ruse is successful, the ripe female will dutifully attempt to transfer her eggs, losing her entire clutch in the process. Suffice it to say, the seahorse breeder should try to avoid anything that might cost a well-conditioned female her clutch of eggs.

It should be noted that this type of competition and aggression is an artifact of captivity and does not occur in nature. The heightened coloration and increased activity exhibited by seahorses during such interactions makes them very conspicuous and vulnerable to predators in the wild. Grappling with rivals and competing for mates requires seahorses to release their grasp on their holdfasts, which is very risky in the ocean, where tides and currents can sweep an unattached seahorse away (Vincent, 1990). When only a trio is involved, mating can still take place once the competition is settled and two of the seahorses pair up. Nonetheless, the competition prior to pair formation costs the seahorses heavily in terms of wasted energy and resources, and the loser will continue to compete for food, consuming 1/3 of the live foods that are offered thereafter. That’s not what you want when you’re trying to condition a male and female for breeding.

The situation is far worse when more than three unattached seahorses are kept together. [4]When many ”eligible” seahorses are crowded together, none of them can establish a home base in which to operate and carry out a complex 3-day courtship unmolested. Normal courtship patterns are disrupted, and mating attempts may be aborted or abandoned altogether in the face of constant interference from potential rivals. Under these difficult circumstances, courtship and breeding can grind to a halt.

When it comes to breeding the larger species of seahorses, keeping more than one unpaired male and female together is a common mistake. Such crowding is an unnatural condition–a sure-fire way to inhibit courtship that often prevents large seahorses from mating successfully in captivity.

Solution: Limit yourself to one male and female per tank. This rule applies to unpaired seahorses only–not pair-bonded couples. Most species mate for life, and such competition does not occur among mated pairs. Therefore, more than one established pair can be kept together if the aquarium is large enough. Dr. Amanda Vincent, the world’s leading authority on seahorse reproduction, suggests a minimum of 100 liters/25 gallons for two established pairs (Vincent, 1995).

[The dwarf seahorse (Hippocampus zosterae ) is an exception to this rule. Due to its diminutive size, it is largely immune to the stresses of overcrowding, and the pygmy pony will continue to pair up and reproduce when kept in large groups. For instance, pet dealers must occasionally crowd large numbers of fish in cramped quarters due to a lack of space, including dwarf seahorses. Robert P.L. Straughan was once forced to keep 300 H. zosterae in a 10-gallon tank in such a situation, and was pleasantly surprised to find that over 100 of them managed to pair up and mate nonetheless (Straughan, 1961). The tank was heavily planted with Crassifolia, and the pygmies apparently felt right at home despite the crowding.]

Mistake No. 3 – Tank-mates in the Breeding Set-Up:

This point also begs the obvious, but if you are interested in breeding seahorses, a male and female should be given a suitable tank all to themselves. Seahorses are shy, secretive creatures that rely on camouflage as their sole means of protection. During courtship and breeding, however, they suddenly become quite conspicuous, exchanging their drab, cryptic coloration for bright courtship colors. The male and female are at their most brilliant at the climax of courtship when they rise for the actual copulation–a brief belly-to-belly coupling which takes place well above the bottom.

Needless to say, the brightly-colored seahorses are extremely vulnerable as the female transfers her eggs to the male’s pouch while hanging suspended in midwater–totally exposed, entirely defenseless, and wholly preoccupied by the task at hand–and they will not put themselves in this vulnerable condition if they feel threatened in any way. In a small tank, even the normal day-to-day activities of harmless, nonaggressive tank-mates, such as small blennies and gobies, may be enough to inhibit courtship and mating. Including so much as a pipefish (a close relative of the seahorse) in the breeding tank is a mistake. Innocuous as it is, a pipefish while still eat more than its share of food, making it more difficult to keep the seahorses in top condition.

Solution: Include no tank-mates or companions of any kind in your seahorse breeding tank. The only exception is if you are keeping your breeders in a reef tank set-up specially for seahorses. Reef systems are generally considerably larger than the typical seahorse breeding tank, and their sophisticated filtration systems maintain optimum water quality. Sponges, gorgonians, and macroalgae provide natural surroundings, and the abundant amphipods, isopods and countless tiny crustaceans that come to populate such systems provide the hungry ‘horses with an opportunity to ”graze” between meals. Seahorses thrive under such conditions and will often breed exceptionally well in a mini-reef.

Mistake No. 4 – the Dimensions of the Breeding Tank:

Some breeding projects are doomed to failure from the moment the aquarist picks out the aquarium for his seahorses. This can happen when a hobbyist selects a tank that is simply too shallow for the type of ‘horses he wants to raise. Seahorses are vertically oriented, and their upright swimming style is best suited to tall aquaria. More importantly, they rise vertically through the water column in order to mate, and if the aquarium is too shallow, they will be physically unable to copulate and transfer the female’s eggs into the male’s pouch for fertilization (Vincent, 1995). This is an important consideration when breeding the largest species such as Hippocampus ingens, kuda, abdominalis, erectus and reidi.

As a general rule of thumb, seahorses must have two full body lengths of open water (top-to-bottom swimming space) above the substrate in order to mate comfortably. This will allow them to swim upwards for one full body length when they rise from the bottom to copulate. In other words, if you want to breed that prize 10-inch Hippocampus kuda of yours, you will need to provide him and his mate with a tank that is at least 20-inches tall; 24 inches of height would be safer.

When selecting a breeding tank, bear in mind that the ”two-body-lengths” rule applies to the depth of the water in the aquarium, not the height of the tank per se. If you keep the water level in the tank an inch from the top and have an inch of calcareous gravel or crushed coral on the bottom, that 12-inch tall aquarium only has 10 inches of vertical swimming space. For example, a pair of 7-8 inch Hippocampus erectus may have difficulty mating in a tank that is only 16-inches high, since they need around 15 inches of vertical swimming space for the copulatory rise, and you must account for the air space at the top of the tank as well as the depth of the substrate. (Reef tanks can sometimes be a problem in that regard, since the substrate of base rock topped off with live rock and corals is often built up quite close to the surface in order to provide the delicate invertebrates with sufficient light. Large seahorses will often thrive in such a set-up, yet be unable to breed due to a lack of swimming space.)

Solution: If your breeding tank is already up and running, it’s up to you to select a seahorse species that can mate comfortably in a tank of those dimensions. If your only available tank is 12-inches high, with a water depth of perhaps 10 inches once filled, then your choice is limited to smaller seahorses such as Hippocampus breviceps, whitei, fuscus or zosterae. For larger seahorses, Dr. Amanda Vincent recommends a tank at least 45cm or 18 inches tall (Vincent, 1995).

If you have the luxury of purchasing a new breeding tank, decide on the type of seahorse you wish to raise beforehand, and then choose an aquarium that will provide twice as much vertical swimming space as the maximum length that species attains. In general, if you have your choice of, say, a 20-30 gallon High or a 20-30 gallon Long tank, the seahorse breeder should opt for the high version.

At the same time, avoid cylindrical tanks and hexagonal models which may lack adequate bottom space. Seahorses spend considerable time moving across the bottom of their tanks, particularly during courtship displays such as the Maypole dance and the parallel promenade. The tank you select for breeding must have sufficient bottom space to accommodate this type of side-by-side synchronized swimming. Experts suggest providing an aquarium of at least 60-100 liters/15-25gallons for a mated pair of large seahorses; two established pairs can safely be housed in same aquarium providing it holds more than100 liters/25gallons (Vincent, 1995).

Mistake No. 5 – Aquarium Decor:

Many hobbyists mistakenly believe that the breeding tank should be sparsely furnished, perhaps with nothing more than a few holdfasts and a bare bottom. (Such sterile environments are commonplace when seahorses are being maintained under laboratory conditions.) A Spartan set-up such as this facilitates feeding, water changes and maintenance, in general, but it can adversely affect the behavior of the inhabitants and prevent seahorses from breeding.

Hippocampus relies on camouflage and remaining hidden for its very survival. Seahorses can thus become distressed and agitated if their tank is too barren to provide adequate cover (Vincent, 1995). This is particularly true during courtship and mating when the increased activity level and heightened coloration make them highly conspicuous and vulnerable, and breeding may be severely inhibited under these conditions.

Nevertheless, the opposite extreme is equally undesirable, and it’s important that the breeding tank is not overly cluttered. Dense thickets of plants and intricate clusters of coral provide perfect hiding places for the seahorses’ prey, making it difficult for them to feed as well as cramping their courtship activities. The breeding tank must provide sufficient shelter, yet still offer adequate space for the pair to conduct their courtship maneuvers and carry out their dancelike displays.

Solution: Decorate the breeding tank so there is plenty of cover at either end, while leaving the center of the aquarium bare to act as a sort of ”dance floor” for the seahorses’ breeding ballet. I prefer to place a medium-sized live rock surrounded by taller holdfasts at either end of the tank, leaving only a substrate of coral sand or crushed shell in the middle of the tank. Position the holdfasts so that there are a few at the back of each rock and another group arranged in front of it. This allows the seahorses to anchor themselves to one set of holdfasts while remaining screened or shielded behind the other. The seahorses can duck down behind the rock or escape into hidden corners at either end of the tank whenever they feel the need for more privacy, yet there is still plenty of elbow room for maneuvering in the center third of the tank.

The courting couple will take hold of a hitching post at one end of the tank and use it as a pivot point for their circling Maypole dance, then cross the bottom in tight parallel formation and repeat their Carousel-like cavorting around a holdfast at the opposite end of the aquarium, only to swim side-by-side across the bottom back to where they started. Back and forth, they will repeat their stately promenade, pausing just long enough at either end to perform their twirling dance around a makeshift Maypole.

The best holdfasts or hitching posts are seahorse trees and soft plastic plants designed for marine aquaria. Imitation sea-whips, gorgonians, sea-fans and seaweeds add a colorful touch of realism, but live marine plants are always a welcome addition that make seahorses feel right at home.

Mistake No. 6 – Photoperiod:

For many seahorse species, it is not the falling water temperatures or the drop in salinity due to monsoon rains that brings breeding to a halt as winter approaches. Rather, it is the decrease in hours of daylight that determines the breeding season.

The dwarf seahorse, Hippocampus zosterae, is a good example of this phenomenon. It stops breeding when the period between sunrise and sunset is less than 11 hours, and reproduces best when the days are longer than 12 hours (Strawn, 1954).

Consequently, if your breeding tank is not provided with an adequate photoperiod, chances are your seahorses will not breed. Period. Kirk Strawn recounts how a pair of prolific dwarfs bred continuously for him until their tank had to be moved into a dimly lit room while his aquarium room was being painted (Strawn, 1954). The moment they were moved to the darkened room, breeding ceased immediately, as if it had been turned off with a switch. Now you know why the seahorses never mated in that tank with the fancy timer that turned the light fixture off after precisely 10 hours!

Solution: Keep your seahorse breeding tank lighted for a least 12 hours every day. Strawn successfully bred and raised Hippocampus zosterae through successive generations (Strawn, 1954) by furnishing them with constant light (photoperiod: 24L/0D). However, since courtship is conducted primarily in the twilight hours just after dawn, Dr. Amanda Vincent recommends using a cycle of 3 hours half-light/10 hours full light/3 hours half-light/8 hours darkness (Vincent, 1995). The half-light periods can be easily furnished by positioning a room lamp a short distance away from the breeding tank, and will provide your seahorses with a simulated dusk and dawn.

Mistake No. 7 – Unshielded Airstones:

That seemingly innocuous stream of bubbles rising lazily from your airstone or bubble wand has probably broken up more seahorse romances in the aquarium than hurricanes have in the wild. Airstones are widely used in seahorse set-ups to provide aeration and gentle circulation, but they can wreak havoc in the breeding tank. When courting, male seahorses perform a maneuver known as ”pumping,” in which they inflate their brood pouches to the bursting point and alternately pump water in and out of the dilated opening with their tails anchored to a holdfast. Troubles arise when bubbles are drawn into the brood pouch during this process, causing buoyancy problems. This often happens when a courting male attaches itself to the airline tubing connected to an airstone and begins pumping in the stream of bubbles. For instance, Dr. Amanda Vincent found ”It’s a good idea to hide airstones. Seahorses are subject to many buoyancy problems that may result from or be exaggerated by sitting in airstone bubbles. This problem is especially prevalent around courtship periods and occurs if males dilate the pouch opening in air streams” (”Keeping Seahorses”, Journal of Maquaculture, Winter 1995, Vol. 3, No. 1: pp 1, 5-6.)

Airstones are particularly troublesome because seahorses actually seem to relish basking in the bubble stream and may actively seek out airstones for that purpose. They appear to enjoy the tactile stimulation provided by the bubbles. The small size of dwarf seahorses (H. zosterae ) makes them especially vulnerable to such buoyancy problems, as explained below.

This is how Kirk Strawn describes the problem in an article called ”Keeping and Breeding the Dwarf Seahorse” (Aquarium Journal, October 1954: pp 226-228.): ”Unguarded airstones disrupted many courtships. A courting male pumps up his brood pouch with water until it appears ready to burst. When this action occurs in the stream of bubbles above an air stone, a bubble is likely to be sucked into the pouch producing a disastrous effect on courtship. The male swims over to meet the female. When the air bubble in the brood pouch shifts, he loses balance and floats tail first to the surface. With great effort he swims down to a perch and wraps his tail around it. Firmly anchored, he resumes an upright position. The female comes over and wraps her tail around his. When she moves away he follows, loses his balance, and shoots to the surface. Finally the pair give up trying to breed. These bubbles remain in the pouch unless removed. In nature death would surely result either by the male’s being washed ashore or from its being exposed to predators. In the aquarium a floating male can live indefinitely.”

Strawn then goes on to describe how this recurring problem can be remedied: ”…removing the bubble by inserting a needle into the opening of the pouch…is a more difficult operation on the little dwarfs. It is more easily accomplished either during courtship or following the delivery of young–at which times the opening to the pouch is dilated. Inserting a needle through the entrance of the pouch does not ruin a male for future breeding. A male kept away from females from February until June had bubbles removed on three occasions by puncturing the side of the pouch with a needle and squeezing out the bubble. (The urge to reproduce is so strong that males go through the motions of courtship and may pick up bubbles even if no females are present.) On June seventh he was placed with a ripe, freshly caught female. On the seventeenth I cut a slit in the side of the pouch and removed a bubble and two partly formed babies. By the twentieth [3 days later] the slit was healed over, and he had another air bubble. On the 23rd I partially removed this bubble by forcing a needle through the entrance of the pouch. On the 25th [2 days later] yolk came out when the needle was inserted. On July 5th he gave birth to a large brood after which a bubble was squeezed out of the dilated opening of the pouch without the aid of a needle. The next day he sucked in another bubble while courting. Although removing bubbles does not permanently damage the fish, it is much easier to put a fence, such as a cylinder of plastic screen, around the air stone and its rising stream of bubbles” (Strawn, 1954).

Solution: This problem is easily prevented by shielding or guarding the airstone so that seahorses cannot come in contact with the air stream. Enclose the airstone and bubble stream within a length of large diameter plastic tubing that has been well-perforated or screen it off behind a cylinder of plastic window screen (the size of the mesh must be too small for the seahorses to perch on.)

Mistake No. 8 – Midwater Turbulence:

Seahorses ascend through the water column together in order to mate, and the actual transfer of the eggs takes place while the couple is suspended in midwater or slowly sinking towards the bottom. Coitus is marked by an extremely awkward, fleeting embrace–really no more than a brief belly-to-belly bumping–during which the female may deposit well over 1,000 eggs in the males pouch within 5-10 seconds. Many difficult and delicate maneuvers–which sometimes wind up with the partners aligned at right angles– are required to bring the pair into proper position for this most improbable of merging. Numerous false starts and abortive attempts are ordinarily involved, with the frustrated pair separating to rest on the bottom between times, before success is achieved. (If you have never had the privilege of watching your seahorses mate, imagine newlywed skydivers attempting to consummate their marriage in free-fall; that’ll give an idea of how difficult copulation can be for seahorses, particularly if it’s an inexperienced pair. As you can imagine, the last thing they’d want to contend with at the moment of truth is swirling air currents or a little wind shear!)

The point is that seahorses are feeble swimmers, and if they encounter too much turbulence as they rise to mate, the buffeting can make copulation and the tricky egg transfer a virtual impossibility. The smaller the seahorses, the more difficulty they will have negotiating currents in the aquarium. (Picture a clumsy, super cargo plane attempting to pull off a tricky midair refueling with an overloaded tanker. If there’s too much turbulence at the crucial moment, the cargo plane will unable to make the critical connection with the tanker, and the mission will have to be aborted.) Likewise, if the water currents are too strong at midwater in the breeding tank, seahorses will be unable to achieve coitus and breeding will be disrupted. Eggs may be spilled and entire clutches may be dropped if buffeting dislodges the ovipositor from the male’s pouch during the egg transfer, making this problem immediately apparent to the observant aquarist. When a female loses her eggs in this manner, she will not ripen another clutch until the pair’s normal gestation period has passed (Vincent, 1990). If the problem persists, the pair may simply give up and stop trying to breed altogether.

Excessive turbulence often complicates life for seahorses in reef systems, since brisk water moment and vigorous wave action are requirements for many corals and reef animals. But buffeting can also become a problem in standard set-ups, since power heads, spray bars from canister filters, and the outflow from external hang-on filters are normally adjusted so they roil the surface of the water to facilitate efficient gas exchange. This results in cross-currents and turbulence in the upper 1/3 to 1/2 of the aquarium, where it presents a problem for seahorses as they ascend through the water column to mate.

Solution: Use air-driven under-gravels and/or sponge filters in the breeding tank and adjust the airflow to provide gentle circulation. Use well-shielded airstones if extra aeration or water movement is desired and adjust the air stream so it merely ripples the surface. Reef keepers should limit themselves to large seahorses such as H. ingens, kuda, abdominalis, erectus, angustus and possibly reidi, which are better able to handle a significant current. If eggs are being spilled or lost in the reef tank, try to provide an area of relatively slack water in one corner of the tank where your seahorses can rise to mate undisturbed.

Mistake No. 9 – Mechanical Vibrations:

The medium of water transmits certain sounds wonderfully well–far better than air, in fact–and like all fishes, seahorses have organs specially designed to detect such vibrations. Indeed, the ”good vibes” seahorses give off during their displays of reciprocal quivering play an important role in courtship.

Unbeknownst to most aquarists, seahorses are also sensitive to external noises and outside sources of vibration, certain frequencies of which can totally shut down breeding. For instance, I know of one recent laboratory study investigating the courtship habits of Hippocampus zosterae that was severely hampered by this phenomenon until it was realized that the inexplicable lack of breeding was due to mechanical vibrations that adversely affected the seahorses and disrupted their normal behavior. The problem was quickly corrected and the study of the mating behavior of zosterae was eventually an unqualified success.

In a case like this, the offending device may be a clunky air pump or compressor, the buzzing ballast from an aquarium reflector, or the rattling impeller from a noisy power filter. Or the source of vibrations may be something totally unrelated to the aquarium, like a nearby clothes washer/dryer, dishwasher, stereo, television or some such appliance.

Solution: The only way to totally eliminate this sort of setback is to choose the location for the breeding tank with care, dampen all potential sources of shock and vibration, and provide a thick pad beneath the tank to deaden vibrations and soften any shocks that might otherwise be absorbed through the base of the aquarium. The aquarium pad should consist of a sheet of cork or styrofoam at least 1/2-inch thick that extends slightly beyond the base of the aquarium on all sides.

The aquarium should be situated in a relatively quiet room away from major traffic areas, blasting stereos, blaring TVs and noisy kids. If you have modified your laundry room, utility room, or workshop so it can do double duty as your fish room, you may want to find a less mechanically-cluttered area for your seahorses. If you’re dealing with a balky air compressor, keep it in another room and run a separate air line from there to the aquarium, if possible.

Other damping measures include mounting noisy equipment such as air pumps on thick blocks of foam rubber. Try using a 4-6 inch block of foam with a shallow 1-2 inch deep cut out area that conforms to the contours of the device in question to hold it securely in place. Raise the aquarium reflector above the rim of the tank so that it is not in direct contact with the cover or the rim of the aquarium itself. The reflector can either be suspended over the tank or propped up on shims of cork, styrofoam, or heavy cardboard. The idea, as far as possible, is to isolate the seahorse breeding tank from outside noise and vibration.

However, the average aquarist need not be overly concerned about mechanical vibration. When it crops up, it is more of a quirk than a common, ever-day problem. Under normal circumstances, placing a cork or styrofoam pad underneath the breeding tank is sufficient proof against shock and vibration.

Mistake No. 10 – Water Conditioners:

I had long believed that the only important aquarium parameters that the seahorse breeder needs to monitor are specific gravity, temperature, and the levels of ammonia and nitrite in the tank. It had been my experience that given proper aquarium maintenance, regular partial water changes, and the addition of Caulerpa and other marine plants, the pH and levels of nitrates and trace elements would pretty much take of themselves. I felt the use of various aquarium additives, replenishers, and water conditioners was therefore unnecessary and, in many cases, counter-productive in the seahorse tank.

Over the years, however, a growing body of evidence has accumulated to the contrary. I am now convinced that such supplementation in the following three areas can dramatically influence breeding success: an adequate level of bioavailable calcium must be maintained, trace elements must be replenished, and nitrates must be kept under control. Let’s examine the facts that support these conclusions.

Item: Male seahorses are now believed to provide calcium and other inorganic ions to the developing young in their pouches. It is thought that males supply inorganic ions but that organic ions are derived from the female (Vincent, 1990). For example, radioactive labeling proved that male H. erectus contribute calcium to the pouch fluid, which is taken up by the embryos and probably incorporated in their skeletons. Work on pipefish has likewise established that morphological structures exist which probably transport inorganic ions from the father to the embryos, and likewise demonstrated that embryos take up water and inorganic substances, but not organic substances, from the male (Vincent, 1990). Female seahorses, on the other hand, are known to supply organic ions to the fetal fry via the yolk (Masonjones and Lewis, 1996). Deficiencies in calcium and other mineral ions could thus adversely affect reproductive success or prevent breeding altogether.

Item: Heather Masonjones found that calcium supplementation improved the reproductive success and survivorship of Hippocampus zosterae in her 1996 study of the courtship behavior of the dwarf seahorse (Masonjones and Lewis, 1996).

Item: Seahorses reproduce exceptionally well in reef systems. No doubt there are many factors that contribute to this success. Mini reefs provide seahorses with optimal water quality, natural surroundings, and an abundance of natural plankton to graze on between meals. But reef keepers also dose their systems with calcium hydroxide and a host of trace elements for the benefit of the hard corals and invertebrates which absorb nutrients from the water, and the denitrifying ability of the live rock combined with sophisticated filtration means reef tanks have very low levels of nitrate as a rule. I feel the levels of calcium, trace elements, and nitrates in such systems may be primary factors as to why seahorses breed so readily in the mini reef.

Item: Anecdotal reports from knowledgeable hobbyists indicate the trace element/calcium supplementation triggers mating among seahorses that had previously failed to breed.

For example, consider the experience of Carol E. Keen, a professional fish breeder who has turned her attention to seahorses in recent years. She is now working with Hippocampus kuda, reidi, and zosterae among other seahorse species. She has nine years experience breeding and raising fishes of all kinds[1], and helps marine collectors and wholesalers to identify the different breeds of seahorses they handle so they will know how best to care for them and provide them with optimum conditions.

Keen had male and female Brazilian seahorses, Hippocampus reidi, which paired up shortly after the female was introduced to the aquarium. For more than a month, this couple courted nearly continuously but failed to breed. This is very unusual, since courtship is the prelude to mating. Normally the third day of courtship is climaxed with the copulatory rise during which the female transfers her eggs to the male’s pouch.

The fact that mating was delayed for so long in this pair-bonded couple indicates that something was lacking in the captive environment which prevented them from breeding. The logical candidates for this lack were diet and the aquarium water itself.

In this case, we can rule out a dietary deficiency. Carol Keen cultures a greater variety and quantity of live foods for her fish breeding operation than anyone I know, and her brood stock enjoy a superb diet. She kept this pair of reidi stuffed to the gills with Artemia-enriched ghost shrimp supplemented liberally with live Gammarus.

Keen suspected something was lacking in the aquarium water, which was kept at zero ammonia and nitrite, and showed about 0.10 ppm nitrate. Consequently, she began using a new type of automatic trace element replenisher[2] which cannot be over- or under-dosed. It consists of specially-formulated mineral blocks which dissolve only as needed to restore and maintain the levels of calcium, strontium, and all essential trace elements at the same levels found in the ocean.

Keen noticed an immediate change in the seahorses’ behavior, which swam over to bask in the bubbles released as the block reacted with the aquarium water. Before another gestation period had passed, the male reidi was pregnant for the first time, and delivered a normal brood weeks later. The stallion out-lived his first mate and went on to pair up with a new female, with which he subsequently produced a second brood.

Keen is convinced the trace element replenisher triggered breeding in her reidi. She makes a good case–nothing else in their diet or aquarium parameters had changed to account for the matings.

The evidence is further bolstered by Theresa Ulrich’s experience breeding Hippocampus kuda and H. zosterae. Theresa is an accomplished marine aquarist and avid seahorse breeder who started out keeping kuda in artificial saltwater made from mineral-rich well water from a nearby nature preserve. She performed 10%-20% weekly water changes religiously, using the same mineralized well water, and her diligence was rewarded when her male kuda began courting shortly after she added a large female to his tank. Within a few days, the couple had successfully bonded.

About this time, Ulrich switched from well water to dechlorinated tap water and adopted a monthly schedule for partial water changes. After making these adjustments, there was no recurrence of this initial success. In fact, for months thereafter, there was no further sign of courtship, bonding, or breeding among any of her kuda or the colonies of dwarf seahorses (Hippocampus zosterae ) she had added in the meantime.

Analyzing this situation, Ulrich realized her former water exchanges using well water must have contributed significant amounts of certain minerals to her aquarium water, and that this mineral component of the water might be lacking or deficient under her current system. Consequently, after much urging, she began using the same trace element replenisher Carol Keen was experimenting with, and achieved similar results.

After regular additions of the replenisher blocks, a second male kuda she had kept for three weeks bonded with a newly-added female, and Theresa witnessed their first mating on the third day of courtship. This was followed by a renewed flurry of courtship and bonding among her dwarf seahorses, culminating with several successful matings. Again it appears the specially-formulated replenisher blocks seemed to stimulate pair bonding and breeding.

Since then, Theresa Ulrich has also determined that the level of nitrates in the aquarium also affects the behavior of her seahorses. She has found that breeding is inhibited among her larger seahorses when the concentration of nitrates reaches 0.20 ppm or higher, and that mating is adversely affected among dwarf seahorses at a concentration of 0.10 ppm nitrate. Ulrich reports excellent results using a new Bacterblend [3] for saltwater aquariums to reduce nitrate levels in the aquarium to zero, with a corresponding increase in breeding success.

The accumulated weight of such evidence has convinced me that breeding in seahorses can be impaired if the concentration of nitrate in the aquarium is too high or the levels of bioavailable calcium or certain trace elements are too low. If courtship persists indefinitely with no sign of mating, or if all else seems well, yet your seahorses show no interest in courtship and bonding, suspect a problem with one of the above parameters.

Solution:

(1) Breeding seahorses can be provided with adequate levels of calcium in either of two ways–by enriching their food supply or by enriching the aquarium water itself. For instance, Heather MasonJones was successful breeding zosterae by enriching the brine shrimp she fed them with Kalkwasser (Masonjones and Lewis, 1996). Other aquarists prefer to add Kalkwasser (calcium hydroxide) directly to the breeding tank via an automatic doser in the same manner as many reef keepers enrich their systems.

(2) Replenish trace elements regularly in the breeding tank. This is especially important if you are using continuous activated carbon filtration or a protein skimmer on your seahorse tank, since these are notorious for removing trace elements. SEA-LAB Formula No. 28 is an excellent choice for this, since it automatically maintains the levels of essential trace elements while replenishing calcium at the same time.

(3) Keep the level of nitrates in the breeding tank below 0.10 ppm at all times. A lush growth of Caulerpa and other macroalge, regular partial water changes, and good aquarium maintenance can all help keep the nitrate level down. But if problems with nitrate persist, stronger measures may be required. Denitrators are now available, but additives that can lower nitrate levels are a more economical alternative. Nitrate Reducer has a proven track record in that regard and is the product Carol Keen and Theresa Ulrich recommend.

Final Hurdle – Incompatibility:

This problem is largely beyond the aquarist’s control. The best way to obtain a mated pair of seahorses is to acquire healthy, freshly-collected brood stock and introduce a single male and female into a suitable breeding tank all their own[4]. But this by no means assures success, since either partner may reject the other at any stage of the ensuing three-day courtship.

The most common cause for rejection is a discrepancy in size. Seahorses tend to select mates of equal or greater size since both males and females can benefit from robust partners (Vincent and Sadler, 1995). Males prefer large females which can provide bigger clutches and eggs with a greater supply of yolk, thereby producing more progeny. Females likewise prefer robust males, since the bigger the brood pouch, the more eggs the male can carry and the more offspring the pair can produce. (Excess eggs that are unable to implant in the placenta-like lining in the male’s pouch fail to develop and are wasted.) Thus, if you attempt to pair up seahorses that differ considerably in size, there is a very good chance that the undersized partner will be rejected. When considering brood stock, it is important to select males and females that are closely matched in terms of body size and weight.

But when it comes to seahorses, such matchmaking is far from an exact science. Even under the most favorable circumstances, when the aquarist has carefully selected prime specimens of comparable size, one of the partners will still be rejected for no apparent reason in a certain percentage of the proposed pairings.

For example, in one laboratory study of Hippocampus zosterae, 4 out of 19 pairs of seahorses specially selected for similarity of body size failed to court or mate (Masonjones and Lewis, 1996). This indicates that despite our best efforts, we can still expect roughly 1 out of 5 pairings to fail.

Fortunately, these unsuccessful pairings can be detected early on and are easy to remedy should they occur. When single or unpaired seahorse are first placed together in the aquarium, they ordinarily begin a three-day courtship shortly thereafter to determine compatibility. The initial stages of courtship usually begin the same day they are introduced, often within hours and sometimes within minutes of their first meeting[5].

If the courtship is successful, it will result in mating and the formation of a permanent pair bond. Likewise, if the pairing is unsuccessful, the courtship will break down at some point during the first three days (Vincent, 1990; Masonjones and Lewis, 1996). Either way, the first three days will tell the story. Most pairings which are unsuccessful fail during the initial phases of courtship, often on the very first day.

However, courtship is often confined to the dawn hours shortly after first light. The diligent aquarist who wishes to monitor the progress of a new pairing must therefore observe them carefully for the few hours after the aquarium lights go on, especially during the first 3 or 4 days after the couple was introduced. Here’s what to watch for:

The male and female will approach each other shortly after first light and begin the initial phases of courtship. At every step in the process, whenever one of the seahorses makes an advance, its partner must respond accordingly. When one seahorse brightens and approaches the other, its partner should brighten in return. And if the male begins to put out the vibes with a seductive display of full-body quivering, the female should reciprocate in kind. Likewise, when the female begins to ”point” in the later stages of courtship, the male must react by ”pumping” or echoing her with a ”point” of his own. Invitations to dance must be accepted and so on.

If that does not happen–if each overture is not answered with an appropriate response–the lines of communication will break down, courtship will come to a halt, and the pairing will fail. If one seahorse brightens in coloration yet its prospective partner remains dark, or if the quivering of one seahorse is ignored by the other, something is seriously wrong and the courtship cannot advance to the next stage.

Courtship typically reaches its climax on the morning of the third day, culminating with the copulatory rise. Therefore, it should be obvious whether the pairing has failed or the seahorses have bonded by midmorning of the third day. If they are incompatible, the seahorses will not brighten or greet one another. There will be no quivering, no Maypole dance, no parallel promenade. The female will not ”point,” the male will not ”pump,” and there will be no rises.

But the real giveaway is the seahorses’ appearance. Prior to mating, the female will hydrate her ripened eggs, becoming visibly swollen and rotund in the process. And, of course, the male’s pouch will become bloated after the transfer of the eggs. So just prior to mating, the abdomen of the ripe female will be noticably rounded or convex, whereas the male’s empty pouch will be shrunken and concave in appearance. Immediately after the egg transfer, however, the situation is suddenly reversed and the female’s abdomen will become sunken and concave while the male’s pouch is now swollen with eggs (Vincent and Sadler, 1995). But if the pair is incompatible, the female will retain her normal lithe appearance and the male’s pouch will remain flaccid throughout. The seahorses will resume their usual drab coloration and remain some distance apart, not interacting in any way.

So the bad news regarding seahorse compatibility is that the aquarist can do everything right and still fail to obtain a mated pair roughly 20% of the time. The good news is that incompatibility is hard for the attentive aquarist to miss and easy to overcome.

Solution: The obvious cure for this problem is to replace one of the partners and try again. Since it’s usually the female who rejects the advances of the male (Masonjones and Lewis, 1996), it makes sense to replace the female, in case she’s a fickle filly who sets impossibly high standards for her stallions, and start over. Select another healthy female of equal or slightly smaller size than the male, and the odds are overwhelmingly in your favor that the new pair will prove to be a match made in heaven.

However, sometimes the best results are obtained by leaving the first female in place when you add her replacement to the breeding tank. Yes, under ordinary circumstances, this could create a level of competition[6] that would be disruptive and undesirable. But in a case where the first female has already rejected the male, there will be little or no interference on her part. Yet, at the same time, the mere presence of a potential rival will often stimulate the new female’s interest in the only man in town and spur her on in the ensuing courtship. And, just occasionally, the appearance of a second female causes the finicky filly to reconsider her judgment, and it is the original femme fatale who bonds with the stallion after all.

Either way, breeding will commence shortly thereafter, and the aquarist’s worries will finally be over. That is, until he realizes he will soon have a whole herd of hungry horselets on his hands. Now’s the time to kick your brine shrimp hatchery into high gear and start some micro-algae and rotifer cultures brewing.

REFERENCES

Giwojna, Pete. 1990. A Step-By-Step Book About Seahorses. T.F.H. Publications, Inc.: Neptune City, New Jersey.

Masonjones, Heather D. and Lewis, Sara M. 1996. Courtship behavior in the dwarf seahorse, Hippocampus zosterae. Copeia (3): pp 634-640.

Straughan, Robert P.L. 1961. Keeping Seahorses. All Pet Books, Inc.

Strawn, Kirk. 1954. Keeping and breeding the dwarf seahorse. Aquarium Journal Volume 25, Number 10: pp 215-218, 227, 228.

Vincent, Amanda C.J. 1990. Reproductive Ecology of Seahorses. Ph.D. Thesis, University of Cambridge: pp 42-64.

Vincent, Amanda C.J. & Sadler, Laila M. 1995. Faithful pair bonds in wild seahorses, Hippocampus whitei. Animal Behavior 1995, 50, 3: pp 1-13.

Vincent, Amanda, PhD. 1995. Keeping seahorses. Journal of Maquaculture (Winter 1995) Volume 3, Number 1: pp 1, 5, 6.

[1]Carol Keen runs Fish to the Nth, a growing fish supply business that specializes in hard to locate specimens delivered directly to your door. For more information, see the Fish to the Nth webpage at the following address: http://www.hsv.tis.net/~fish2nth/

[2]SEA-LAB FORMULA No. 28 AUTOMATIC REPLENISHER by:

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Redwood Beach, California 90278

[3]Brand name is +Nitrate Reducer by:

Aquamarine Bio Chem Division

1-517-793-8662 or 1-517-793-1200.

[4] The majority of the time, this will result in the formation of a permanent pair bond. Research has shown that newly-widowed seahorses in the wild tend to accept the first available mate they encounter, most likely due to the scarcity of prospective partners (Vincent and Sadler, 1995). This tendency works in favor of the hobbyist, since the adult seahorses the aquarist obtains were most likely separated from their mates and widowed during the collection process. They are therefore likely to pair up with the first sexually mature member of the opposite sex they find that has no mate.

[5] Lensmaster Photos often takes advantage of this predictability to get good photographs of seahorses. For example, when we needed photos of dwarf seahorses in full color, we obtained several new, unmated adults and introduced then to a 2-1/2 gallon display tank which housed our colony of zosterae. The newcomers and the unpaired pygmies in the colony immediately approached one another and initiated courtship. We knew that for the next 2-4 days the seahorses would be at their brightest and most active, and we would have ample opportunity to shoot good color photos of courtship and possibly even mating.

[6] This is one situation where the seahorse breeder can sometimes benefit from keeping a trio together until a mated pair emerges, but only if the threesome consists of two females and one male. When females vie for the same male, they compete by increasing the duration, vigor, and intensity of their dancing and displays of ”pointing,” not with any sort of physical contact. Tail wrestling, snapping at rivals, and tug-o’-war matches are simply not in the female’s repertoire.

[1] Carol Keen recommends the following quick, easy test for determining whether or not that suspicious bump on your seahorse is actual a sea louse dug in on its host–prod it and try to make it move. Argulus are highly mobile and will often betray their unwelcome presence by attempting to scuttle away from a noxious stimulus such as your finger or a pointed probe.

[2] When pair-bonded seahorses divvy up the available resources in this manner, it makes good sense for the males to stay close to home while their mates forage over a much larger range. This is because pair-bonded males are always pregnant, and therefore hindered by their swollen brood pouches. A pregnant male’s bloated belly impairs its mobility and makes the expectant father more conspicuous to predators, a deadly combination should the pregnant papa stray too far from home. So the male stays put, becoming the center of his faithful filly’s relatively far-flung universe, as she searches for food over a bigger area.

[3] When different sexes are involved, however, interspecies match ups don’t always result in violence. When a male and female of different species are housed together, the result may be courtship, not combat, and I have been hearing more and more accounts of hybridization recently. For example, the last report I know of involves a male kuda that was smitten with a yellow reidi female (C.E. Keen, personal communication). This male kuda had previously rejected a number of other females of different types, which he seemed to recognize as belonging to different species and thus unfit. (By rejected, I mean he forcibly ejected these females from his presence–reacted to them so violently they had to be removed from his aquarium.) But he instantly accepted the reidi female, possibly because they were both large yellow seahorses with smooth exoskeletons of rather similar appearance.

Even more surprising, Greg Hiller reports an example of hybridization between two very dissimilar seahorses (see photos)which nonetheless managed to overcome their ‘language barrier’ and successfully court, pair up, and mate repeatedly. In his case, it was a female histrix which bonded with a male Tiger Tail seahorse and produced several broods of healthy fry. No word yet on whether the hybrids that might result from such pairings are sterile, but Mr. Hiller has successfully raised a young hybrid male which is now nearing sexual maturity, and he may soon be able to provide an answer to this fascinating question.

[4] The size of the aquarium is obviously the limiting factor when overcrowding is considered. The smaller the aquarium and the larger the seahorses, the more acute the problems associated with overcrowding will become. I know of many hobbyists who have managed to breed seahorses that were kept in groups of 4-8 adults–particularly in reef systems, but they invariably enjoyed the luxury of a rather sizable aquarium and must be regarded as exceptions to this rule.