kreisel set up

Dear ocean:

Yes, sir, you are correct — a kriesel nurseries tank is very helpful for raising Brazilian seahorse fry, since the newborn Hippocampus reidi undergo a lengthy pelagic phase of development that may last several weeks.

I would not recommend including live rock or a small refugium in the designed for your kriesel nurseries, however, since that will greatly increase the danger of hydrozoans overrunning the nursery. The problem is that nursery tanks provide an ideal breeding ground for hydroids, which can quickly explode to plague proportions and wipe out all of the seahorse fry, and adding live rock or a refugium to your nursery setup virtually guarantees that hydroids will gain entry as well.

Sooner or later hydroids will appear in any marine aquarium that is receiving regular feedings of rotifers, copepods, or baby brine shrimp or plankton suitable for filter feeding invertebrates. It’s inevitable because they can gain entry into the aquarium in many ways. For example, they are notorious hitchhikers. Both the colonial polyp stage and the free-swimming micro-jellies can thumb a ride on live rock, macroalgae, hitching posts, sand or gravel, specimens of all kinds, or within so much as a single drop of natural seawater (Abbott, 2003). Beware of fuzzy looking seashells! Very often hydrozoans come in on the shells of the hermit crabs or snails we purchase as aquarium janitors (Abbott, 2003). Or they may be introduced with live foods, or even among Artemia cysts, in some cases it seems. They can even be transferred from tank to tank in the aerosol mist arising from an airstone or the bubble stream of a protein skimmer.

It can be very challenging to identify hydroids because there are about a zillion different species of hydrozoans and the different types have different characteristics and are often vary remarkably in appearance. There is considerable variation within the species as well, and the same type of hydroids can appear vastly different depending on the size of the colony and its stage of development, conditions in the aquarium, and their predominant diet. And, of course, the different stages of the life cycle of these amazing animals are so entirely different that they were long believed to be different types of cnidarians altogether, and different species names were often assigned to the same hydroid in different phases of its life cycle. Because they are so difficult to identify and are not easy to distinguished with the naked eye during their initial stages, hydroids often go undetected in nursery and rearing tanks until they begin to take a toll on the fry.

The typical hydroid colony has a stem with a variable number of polyps growing on it, and each of these polyps bears numerous tentacles that are liberally studded with knobby nematocysts (batteries of deadly stinging cells). There are many different kinds of hydroids and they appear in the aquarium in many different guises: many colonies are stalked; some have fingerlike projections, others look like tiny pink fuzzy balls or appear like cobwebs (the webbing kind usually spread along the bottom or grow on the aquarium glass along the substrate). The "snowflake" type of hydroids seem to be particularly common in aquaria, whereas other species look more like crystal chandeliers, and some species form bushy colonies as they grow that serve as microhabitats for Caprellid skeleton shrimp and other tiny crustaceans.

Even a large hydroid colony appears harmless to the naked eye of the untrained observer. It takes a much closer look to reveal the dreaded ‘droid’s lethal nature, as described below:

"Studying the colony under high magnification, one soon becomes lost in an extraordinarily complex, living world–a microcosm in which a beautiful but deadly ballet is conducted on a microscopic scale (Rudloe, 1971). Hungry polyps, some resembling snapdragons, others looking more like daisies or tulips, expand their knobby, translucent tentacles, slowly flexing and languidly waving them about, lulling the observer with their slow-motion ballet — until they abruptly and quite unexpectedly snap up a bit of planktonic life, stinging it, drawing it in with one violent contraction, digesting it, and then re-expanding like a blossoming flower to hunt again (Rudloe, 1971). There are many such polyps in a colony, hundreds of them, each of which is armed with many tentacles and countless nematocysts, and at any given moment, some of them will be dormant and still, some will be expanded and lazily casting about for prey (Rudloe, 1971), and still others actively feeding (Abbott, 2003)."

The feeding or nutritive zooids are the distinct individual animals in a hydroid colony that are responsible for capturing and digesting prey; as such, they bear the nematocyst-studded tentacles. But you need high magnification in order to appreciate the true beauty of living hydrozoans, or to differentiate between different species of hydroids, or to observe the zooids going about their deadly business.

Hydroids are insidious because they start out so small and insignificant, yet spread so quickly under ideal conditions (e.g., a nursery tank or dwarf seahorse tank receiving daily feedings of Artemia nauplii). Many species can spread asexually by fragmentation as a microscopic speck of the parent colony. All of the troublesome types have a mobile hydromedusae stage, which look like miniscule micro-jellyfish, and can spread sexually in this way as well (Rudloe, 1971). The mobile medusae swim about with a herky-jerky, pulsating motion and are often mistaken for tiny bubbles due to their silvery, transparent, hemispherical bodies (Rudloe, 1977). These tiny jellies often go unrecognized until they begin to settle and are discovered adhering to the tank walls. They will have a large "dot" in the middle of their bodies and smaller ones at the base of their nematocysts (Abbott, 2003). Both the polyp stage and the medusa stage sting (Rudloe, 1977) and are capable of killing or injuring seahorse fry. Multiple stings can kill the babies outright, but they are often only injured by the nematocysts, which damage their integument and leave them vulnerable to secondary infections. Many times it is a secondary bacterial or fungal infection that sets in at the site of the injury which kills the fry.

Once they find their way into a dwarf seahorse setup or nursery tank, hydroids can explode to plague proportions very quickly because conditions are ideal for their growth: perfect temperatures, an abundance of planktonic prey that is renewed every few hours, and a complete absence of predators. That is the primary pitfall when including a refuge or live rock in a nursery tank.

In short, ocean, I would concentrate on setting up kriesel nurseries adjusted to maintain the circular kreisel flow at the optimal rate of 10mm/sec, a 12:12 photoperiod at 150-200 Lux, and greenwater added as necessary to maintain the necessary turbidity (i.e., 150,000 cells/milliliter).

The turbidity provided by the greenwater helps keep the phototropic fry evenly dispersed throughout the water column and away from the surface. Jorge Gomezjurado has been very successful rearing Hippocampus reidi and H. ingens fry at the National Aquarium in Baltimore using kreisel nurseries with the proper density of microalgae (i.e., greenwater). Jorge has found that turbidity is an important factor in the juvenile rearing environment for these species and he achieves the proper level of murkiness for optimum results by using algae (Nannochloropsis and Isochrysis) at a concentration of about 150,000 cells per ml (Bull and Mitchell 2002).

Best of luck with your prolific ponies and all their progeny!

Respectfully,
Pete Giwojna

Dear JD:

Yes, sir, culling is an important step for improving a strain of cultured seahorses and is one of the keys to a multigenerational approach to rearing seahorses. But there is a difference between developing a hardy strain of domesticated seahorses at an aquaculture facility and the needs of the home hobbyist, and that different also extends to culling the newborns. Allow me to explain a little more detail.

For starters, let’s examine how selective breeding is carried out at the Ocean Rider aquaculture facility, JD. In the first place, you must realize that Ocean Rider’s captive-breeding program is geared toward increasing the heterogeneity of their livestock, not producing homozygous recessives. As intraspecific hybrids, Ocean Rider farm-raised seahorses enjoy increased vigor and benefit from enhanced genetic diversity compared to wild seahorses or other domesticated seahorses.

Basically, when they begin working with a particular species, Ocean Rider’s approach is to obtain sufficient broodstock from throughout their range to completely eliminate any concerns about inbreeding, and then to pair males and females from different bloodlines in order to achieve intraspecific hybridization. That way, each pairing actually increases the genetic diversity of the offspring, and providing you avoid brother-sister crosses when you subsequently select your breeders for the next generation, each new generation will actually be strengthened (more genetically diverse than their parents) through the phenomenon of hybrid vigor.

This is especially true considering the primary traits Ocean Rider selects for are adaptability, disease resistance, vigor, aggressive feeding habits, and rapid growth. Far from being recessive characteristics that could eventually result in inbreeding, these are all adaptive traits that increase the line’s fitness and improve survivorship. In fact, they are the same sort of traits Mother Nature herself selects seahorses for in the wild to assure survival of the fittest. When nature culls out the weakest and least fit, it is known as "natural selection." It is nature’s way of keeping a species strong, vigorous, and adaptive (i.e., evolving to better fit its niche). The only difference is that Mother Nature is selecting for suitability to their natural habitat, whereas Ocean Rider is selecting seahorses for fitness to captive conditions. In both cases, the selection process assures that the specimens become ever stronger and better adapted to their environmental niche, whether that is the aquarium or the ocean itself.

Practiced in this manner, selective breeding actually strengthens and improves a strain generation by generation, producing seahorses that are progressively hardier and better suited for aquarium life.

Initially, Ocean Rider’s goal is therefore not to rear the maximum number of offspring from each brood, but to assure that the weaker offspring are weeded out at every stage, and that only the fittest fry are selected for further rearing. As a result, it typically takes Ocean Rider several generations to strengthen a new type in this manner before they consider bringing it to market. Even then, before OR makes a new captive-bred line available to the public, they do a test offering in which they sell a limited number of specimens to knowledgeable hobbyists that are experienced seahorse keepers in order to determine how well the new line handles shipping from Hawaii and how well they fare in hobbyists’ tanks. If the new type does not perform up to expectations, it’s pulled off the market for another generation or two of further strengthening and improvement before it’s re-released (each generation takes 6-12 months to become sexually mature, depending on the type).

It’s a good system, and it assures that ORs will only continue to get stronger, hardier, and more trouble free over time as they are become ever better adapted to aquarium conditions. When it comes to selective breeding, nobody else goes to such great lengths to avoid inbreeding and instead increase the genetic diversity of their livestock, and that’s a big part of what makes Ocean Rider seahorses superior to all the rest.

The other primary aspect that makes Ocean Riders so much better than any other seahorses is the fact that Ocean Rider is the one and only aquaculture facility to earn High Health Certification.

In order to earn High Health Certification, an aquacultural facility must first prove that it enforces a strict biosecurity program with rigorous quarantine protocols, and that at no stage in the breeding and rearing process are its livestock ever exposed to open systems or wild-caught seahorses. Secondly, it must withstand intense scrutiny by outside agencies — in this case, primarily from the Controlling State Aquatic Veterinary industry. The monitoring done by these Aquatic Health Specialists includes regular sampling of Ocean Rider livestock for complete necroscopic examinations. Periodically, OR seahorses are selected at random by the State Controlling Vet, euthanized, and autopsied. Their internal organs are examined, tissue sections are taken (multi-organ histopathology), and examined microscopically, along with other laboratory analyses. Only then can Ocean Rider seahorses be certified free of specific pathogens and parasites.

There is a reason that Ocean Rider is the only High-Health seahorse farm and that is because high health certification is very difficult and expensive to attain. It is very costly in terms of the time, energy, resources, and the increased size of the aquaculture facility it requires to meet the demanding high-health standards. You must provide a biosecure area for each species you are working with, follow very rigorous quarantine protocols, and periodically sacrifice a portion of the healthy, mature seahorses you have raised for so many months — just when they are ready to go to market — for complete necroscopic examinations in order to make certain they are free of pathogens and parasites. All of which makes achieving and maintaining High-Health Certification a very expensive proposition. Ocean Rider does it to assure that they are providing the best possible livestock for hobbyists. As always, their primary concerns are not profits but the health and welfare of their seahorses and the benefits cultured seahorses provide in terms of conserving wild populations.

Okay, JD, that’s the way rearing works at a High-Health aquaculture facility. The goal is not to raise the maximum amount of offspring from each brood, but rather to raise only the hardiest and healthiest of the offspring from each pairing in order to improve and strengthen the strain of seahorses over time. (That’s what I mean by a "multi-generational" approach to rearing.) As you can imagine, culling out the less fit offspring is vital for assuring that a strain of seahorses remains hardy and adaptive.

However, the needs of the home hobbyist are somewhat different than the lofty goals of a High-Health aquaculture facility such as Ocean Rider. The home hobbyist is often merely hoping to get any of his or her offspring to survive to maturity, and when that is the case, culling the newborns is not such a priority. Indeed, many home hobbyists find the prospect of culling the baby seahorses to be heartless and cruel and personally abhorrent. That’s just fine; culling isn’t for everybody, and it certainly not a necessity for the home hobbyist. So many home hobbyists prefer to allow natural attrition to do the culling for them, and I have no problem with that whatsoever when it comes to the home breeder.

If you want to call the newborns from the very large broods produced by your H. reidi, JD, remember that the idea is not to remove a certain percentage of the offspring but rather to weed out the weak, runts, infirm, defective or deformed offspring. In some broods, that may be relatively few of the newborns, whereas in other broods, it may be a third or more of the offspring.

If you want to give it a try, JD, begin the culling process by eliminating any stillborn young (up to 1/3 of the entire spawn are born dead in some cases; Bellomy, 1969). Other newborns will be alive but still attached to their yolk sacs, and some of the fry may have obvious deformities (Giwojna, Jan. 1997). Such pug-nosed ”preemies” and crippled specimens must also be weeded out since their chances for long-term survival are very poor (Giwojna, Jan. 1997).

Next remove all of the undersized individuals. You will notice that the fry in every brood exhibit a range of sizes (Giwojna, Jan. 1997). The largest individuals may be almost twice the length of the smallest of the fry. Such "runts" are at a serious disadvantage compared to their larger siblings primarily because their bigger brethren benefit from increased feeding opportunities (Giwojna, Jan. 1997). Not only can they swallow larger prey, they can swim further with less expenditure of energy (Giwojna, Jan. 1997). This allows them to feed on a greater range of potential prey and to capture food more efficiently than the small fry.

Continue the process of elimination with the goal of selecting only the healthiest, most vigorous young for further rearing (Giwojna, Jan. 1997). The idea is to decide how many fry you can reasonably hope to care for, and then cull mercilessly until you reach that number. It sounds cruel, but the colossal task ahead is going to stretch your time, equipment and patience to the breaking point, and your limited resources must be reserved for the fry that can benefit from them the most (Giwojna, Jan. 1997). The harsh truth is that if you try to save the entire spawn, you may markedly reduce your chances of raising any of them. It’s far better to keep a few well-fed babies in pristine water and perfect health than it is to keep a few hundred malnourished fry under crowded conditions, in water of rapidly deteriorating quality, that are certain to languish and die (Giwojna, Jan. 1997).

Bear in mind that if you do not cull out the weaklings, Mother Nature will be happy to do it for you. The disadvantaged fry will still be weeded out and die during the rearing process, but they may jeopardize the healthy fry in the interim by consuming your precious resources, polluting the nurseries, and increasing the chances of disease spreading throughout the nursery. Culling will occur, one way or another, and it’s best for the hobbyist to do it immediately rather than to prolong the suffering and put the healthy young at risk while the less fit fry are slowly eliminated nature’s way.

When culling H. reidi fry, which go through an extensive pelagic or free-swimming phase of development, it is especially important to call out any floaters or surface huggers that have accidentally ingested air. As you know, these planktonic seahorse fry feed at the surface where their prey tends to congregate, drawn to the light, and all too often the newborns take in air along with their food and cannot expel this air. When this happens, it upsets the fry’s equilibrium, and they will float sideways on the surface of the water. Upon close examination of these floaters, a bubble of trapped air can be spotted just below the head (Tracy Warland, pers. com.).

This can often best be observed when you shine a light through your nursery from behind, JD, which will often reveal a bubble of trapped air situated just below the head in the neck or uppermost part of the chest, indicating newborns that have accidentally ingested air, and if they are having any buoyancy problems as a result, it would be a good idea to weed them out since their long-term prospects are very poor.

If you are unsure, retain the newborns for further rearing until buoyancy problems become apparent and then cull out any floaters that emerge during the pelagic phase of their development.

Culling is usually done before the spring are introduced to the kriesel nurseries and the newborns that are weeded out and be removed by hand or by using a baster or pipette or similar apparatus to suck them up along with a little aquarium water.

Best of luck with your latest brood of Brazilian seahorse babies, JD!

Respectfully,
Pete Giwojna