Hippocampus Ingens

Dear TJ:

Ocean Rider’s strain of Hippocampus ingens, known as Gigantes, are among the largest of all the seahorses when fully grown. They can reach a maximum length of 36 cm or 14 inches, which makes them the longest of all the seahorses.

The Ocean Rider Gigantes (H. ingens) are tropical seahorses and they do make compatible tankmates for other tropical seahorses such as Hippocampus erectus and H. reidi. In fact, one of the special offers from Ocean Rider includes a pair of Gigantes (H. ingens) together with a pair of Sunbursts (H. erectus).

Here is my species summary on H. ingens, which will explain all about their aquarium requirements and temperature requirements, TJ:

Hippocampus ingens (Tropical, Pelagic)
Common name: Pacific Seahorse, Pacific Giant or Gigante (US).
Scientific name: Hippocampus ingens Girard, 1858
Synonyms:
Hippocampus ecuadorensis
Hippocampus gracilis
Hippocampus hildebrandi

Maximum size: 14 inches (36 cm).

Climate: tropical: 15°S to 30°N, with the heart of their range from 5°S to 20°N (see discussion below).

Distribution:
Eastern Pacific: from San Diego in California to Mexico, Guatemala, El Salvador, Panama, Columbia, Ecuador and Peru, including the Galapagos Islands (see Discussion below).

Meristic Counts:
Rings: 11 trunk rings + an average of 39 tail rings (tail rings range from 38-40).
Dorsal fin rays: averages 19 soft rays (18-21) covering 2 trunk rings + 1 tail ring.
Pectoral fin rays: an average of 16 soft rays (rays vary from15-17).
Morphometrics:
Snout length: 2.3-2.4 (2.1-2.5) in head length.
Other distinctive characters:
Coronet: medium-high, tilted backwards with five well-defined points, sharp edges or flanges at top.
Spines: variable, from low rounded bumps to well-developed blunt-tipped spines.
Key Features: prominent, long (drooping), rounded, single cheek spines; prominent eye spine (may be broad or almost double); males commonly have a prominent keel; sexually mature females often have a dark patch below the anal fin.
Adult height: 5-12 inches (13-30cm).

Color and Pattern:
Coloration ranges from green, brown, reddish-maroon, and gray to yellow and gold or various shades of brown. In wild specimens, most of the body is mottled dark brown covered with a network of small dark and white spots that coalesce into tightly packed, white scribbly lines running vertically down the body (Bull and Mitchell, 2002, p43). Numerous fine light and dark line markings that radiate around the eyes are a consistent feature that adorns many H. ingens (Bull and Mitchell, 2002, p43), and they may also have white bands around their bodies every 6th or 7th ring.

The captive-bred specimens from the premiere seahorse ranch in Hawaii are a bright golden yellow color over their entire bodies. On some individuals, the bright yellow base coloration is overlaid with a wispy network of fine purplish lines. On closer glance, the lines begin as a string of tiny dots that merge together to form a weblike pattern of thin lines running down their bodies. The fine, lilac-purple lines go very well with the yellow background color, making this a very attractive seahorse.

Breeding Habits:
Breeding Season: in Mazatlan (Mexico), from late September to late May.
Gestation Period: 14-15 days (varies with temperature and diet).
Brood Size: can be huge; up to 2000 is possible, but 60-400 is more typical.
Size at Birth: 1/4" (6-7 mm).
Onset of sexual maturity: typically 8-10 months, but juveniles often go through the motions of reproductive activity (unsuccessfully) as early as 3 months.
Pelagic/Demersal (benthic): the tiny fry undergo a prolonged pelagic phase for their first several weeks or months.

Ease of Rearing:
H. ingens is very difficult to raise. The fry are smaller than H. reidi fry on average and go through a pelagic phase that can last as long as 3-4 months (Eliezer Zúñiga, pers. comm.). Most breeders consider it even more challenging than H. reidi, which is notoriously difficult to rear.

Natural Habitat:
Usually reef-associated, this species is commonly found clinging to gorgonians, sponges, or branching coral on patch reefs in deeper water. H. ingens is a relatively strong swimmer that may venture into waters as deep as 60 meters.

Natural History:
The Pacific giant seahorse (Hippocampus ingens) is typically found in offshore waters (sometimes within the stomachs of yellowfin and bluefin tuna), where it lives amidst the branches of gorgonians and black coral trees (Ref. 5227), which make ideal hitching posts. Most specimens are captured by dredging at 33 feet (10m) or deeper or are taken by shrimp trawlers as an accidental bycatch. Some populations prefer coastal waters with sea kelp and eelgrass at depths of 1 to 20 meters, but it is often found in deeper waters at depths of up to 60 meters (Lourie et al 1999). As a result of habitat loss, overfishing, and local extirpations, its distribution has now been reduced to nine main habitat clusters, scattered from central Baja, Mexico in the north, through Guatemala, El Salvador, Panama, Columbia, and Ecuador to Pucusana, Peru in the south, extending as west as the Galapagos islands (Fritzsche 1980).

Some individuals are caught at surface at night, and these giant seahorses are now believed to be nocturnal in nature. As with H. comes, which is also thought to be nocturnal, there is speculation that the nocturnal behavior of H. ingens may be a recent behavior modification that resulted from heavy fishing pressure (Dames 2000). H. ingens has been over harvested for use in Tradition Chinese Medicine (TCM), which favors large smooth-bodied seahorses such as ingens, and decimated by shrimp trawlers that take a heavy toll because the seahorses are attracted to shrimping grounds as a natural food source. Nocturnal behavior may thus have been selected for in H. ingens because the seahorses that are active by day are accidentally taken in trawls or deliberately collected by seahorse fishers for TCM and removed from the population.

It may be helpful for the hobbyist to think of H. ingens as a giant version of the Brazilian seahorse (H. reidi), to which it is closely related. Hippocampus ingens is the only seahorse in the eastern Pacific, and it is closer genetically to the Atlantic H. reidi than any of its western Pacific counterparts (Dames, 2000). In fact, the two are believed to have diverged from a single ancestral species as a result of the formation of the Isthmus of Panama three million years ago (Lourie et al 1999).

The two species are very similar in their behavior and aquarium requirements, and both follow the same reproductive strategy, delivering huge broods of very small fry after a short two-week gestation period that must undergo a prolonged pelagic period of further development amidst the lipid-rich planktonic soup. Like H. reidi, H. ingens is believed to be monogamous in the wild, pairing up for the length of the breeding season at least (Dames, 2000). It is not known if the Pacific Giant forms permanent pair bonds, however, since they disperse and spend winters in the open ocean (Dames, 2000).

Males mature at a length of just over 2 inches (5.4 cm) in the wild (Groves and Lavenberg 1997), but this is a slow growing species and captive-bred H. ingens typically don’t mature until the age of 10-12 months (Gomezjurado 1988). The breeding season for H. ingens is restricted by water temperature, but not by the onset of cold weather, as in temperate seahorses; rather, it is rising water temperatures in the heat of summer that ends the breeding season for this tropical species (Eliezer Zúñiga, pers. comm.). The Mexican population of H. ingens begins breeding in late September when the water temperatures decreases below 81°F (27°C), and keep breeding until late May when the water temperatures increase above 80°F again (Eliezer Zúñiga, pers. comm.).

Pair-bonded Pacific seahorses produce large broods of 400 or more fry. The pelagic fry are small (6-8mm) and have proportionally larger dorsal fins than the adults to aid them during their free-swimming pelagic phase, which typically lasts 1-2 months (Gomezjurado 1988) but may persist for 3-4 months in some cases (Eliezer Zúñiga, pers. comm.).

Growth is slow but steady in captivity. Females 3 months old are capable of producing eggs, but only in small quantities of 50 or so (Gomezjurado 1988). Juveniles and subadults often practice courting and breeding as early as 3 months, but reproductive success is not achieved until 6-12 months, more often the latter (Gomezjurado 1988). By the end of their first year, young ingens are typically producing offspring of their own.

Preferred Parameters:
The following parameters are based on Carol Cozzi-Schmarr’s recommendations for rearing Hippocampus ingens at the Ocean Rider seahorse farm:
Temperature = range 68°F-80°F (20°C-27°C), optimum 75°F (24°C).
Specific Gravity = range 1.022 – 1.026, optimum 1.0245
pH = 8.2 – 8.4
Ammonia = 0
Nitrite = 0
Nitrate = 0-10 ppm

Suggested Stocking Density: 1 pair of 6-12 month old ingens per 13 gallons (50 liters).

Aquarium Requirements:
The following recommendations are based on Jorge Gomezjurado’s successful rearing program for Hippocampus ingens at the National Aquarium in Baltimore (NAIB). They describe the system he uses for keeping adult ingens at the Aquarium:

Tank: deep, wide tanks (> 1m deep) with a turnover of about 2.5 gallons/min. (10 liters/min.) are recommended.
Filtration: mechanical, biological, and UV sterilization.
Aeration: additional aeration not used in adult tank.
Substrate: live sand.
Holdfast: gorgonians.
Lighting: cool-light fluorescent fixtures maintaining 500-800 Lux.
Photoperiod: 12 hours Light:12 hours Darkness (12:12 L:D).
Temperature: can be kept at 60-77oF (15-25oC) — optimal temp is 73-74oF (23oC).
Nitrite (NO2): < 0.1 mg/l
Nitrate (NO3): < 12.5mg/l
Ammonia (NH4): 0 mg/l
pH: 8.25 — controlled by additions of calcium hydroxide (CaOH).
Salinity: optimal salinity is 34 ppt.
Water change: 10% performed every day.

Juvenile Rearing Tanks:
The following recommendations for nursery and rearing tanks, as well as diet and nutrition are again based on Jorge Gomezjurado’s breeding and rearing program for H. ingens at NAIB:

Hippocampus ingens fry are pelagic, and Jorge reports that circular black pseudo-kreisel design nursery tanks have been used successfully to rear this species, with the proper flows being established by positioning a bubble curtain at one end of the tank (Bull and Mitchell, 2002, p44). He suggests that the fry should be maintained in the nurseries at a density of no more than 24 young per gallon (6 fry per liter) (Bull and Mitchell, 2002, p44).

Water quality and photoperiod should be maintained as described above for the adult tanks, with 10% daily water changes and 150-200 Lux as the optimal light level (Bull and Mitchell, 2002, p44). Gomezjurado has found that turbidity is an important factor in nursery tanks for this nocturnal species. He maintains the appropriate degree of murkiness in the rearing tanks for ingens fry and juveniles by providing good aeration (through airsticks) and using algae (Nannochloropsis) in the nurseries at a concentration of about 100 cells per ml (Bull and Mitchell, 2002, p44). Jorge advises that the optimal water flow for the greenwater nurseries and rearing tanks is 10 mm/sec, and reports that feeding decreases at lower or higher flow rates (Bull and Mitchell, 2002, p44). At the proper level of flow (10mm/sec), the water movement also generates enough turbulence to break the surface tension of the water, which is crucial because it allows the newborns to penetrate the surface and fill their swim bladders with air in order to achieve neutral buoyancy (Bull and Mitchell, 2002, p44).

Diet, Nutrition, and Feeding Techniques:
Jorge Gomezjurado reports that providing a highly nutritious diet for his broodstock is a key element of his successful rearing program for H. ingens because well-fed adults produce larger offspring than adults that receive a marginal diet (Bull and Mitchell, 2002, p44). That can mean the difference between small 6-7mm ingens fry which require rotifers or copepod nauplii as their first food and jumbo 10mm fry which can take newly hatched brine shrimp (Artemia nauplii) right from birth. Jorge finds that feeding his breeding adults a staple diet of enriched frozen Mysis relicta 3 times a day results in large fry that average about 10mm in length and can easily accept Artemia franciscana Instar I nauplii as their first food (Bull and Mitchell, 2002, p44).

At the National Aquarium in Baltimore, enrichment is provided by coating the frozen Mysis relicta with essential vitamins and amino acids, Protein HUFAÒ and Astaxanthene Natu-Rose (Bull and Mitchell, 2002, p44). This staple diet of frozen mysids is then supplemented with frozen krill (Euphasia pacifica), live mysids (Neomysis mercedes), live amphipods (Orchesthoidea sp.), Cyclop-ezee plankton and Selco-enriched adult brine shrimp (Artemia franciscana) (Bull and Mitchell, 2002, p44).

As with all seahorse fry, Gomezjurado finds that providing H. ingens fry with proper nutrition during the first weeks of life is one of the major difficulties in seahorse culture. He finds it necessary to have a chain of live food consisting of phytoplankton (species such as Nannochloropsis aculata and Isocchrysis galvana) rotifers (Brachionus plicatilis), haparticoid copepods (Euterpina acutifrons), small amphipods (Orchesthoidea sp.), brine shrimp nauplii (Artemia franciscana), and larval mysid shrimp (Mysidopsis bahia) ready and waiting for the hungry fry (Bull and Mitchell, 2002, p44). The microalgae (phytoplankton) serve as a source of food and nutrition for the various zooplankton in the chain, and the progressively larger prey items are introduced to the fry and juveniles as they grow (Bull and Mitchell, 2002, p44).

The feeding levels provided at NAIB depend on the stocking densities of the nurseries and rearing, which Jorge cautions should not exceed 24 fry per gallon or 6 fry per liter (Bull and Mitchell, 2002, p44). Recommended feeding densities are 10 rotifers/ml, 15 nauplii/ml, and 3 copepods/ml to start with, with the amounts increased as the fry grow to keep up with demand (Bull and Mitchell, 2002, p44). The water intakes in the rearing tanks are closed or markedly reduced during feeding times. Jorge finds that the gradual transfer from one live food organism to another is easily achieved simply by overlapping feedings at the different weaning stages (Bull and Mitchell, 2002, p45).

The zooplankton that comprise the live food chain at NAIB are enriched with essential vitamins, commercial products of (Omega-3) highly unsaturated fatty acids such as Selco, Culture HUFA, Roti-Rich and Astaxanthene biological pigment Natu-Rose (Bull and Mitchell, 2002, p45). The enriched brine shrimp nauplii (platinum-grade Artemia franciscana cysts) used at NAIB receive special treatment to help keep them germ free. The decapsulated brine nauplii are kept at high salinity (55-60 ppt) after hatching and the culture water is changed every day in order to prevent bacterial proliferation (Bull and Mitchell, 2002, p45). Before use, live food for the seahorses is disinfected in a 10-minute freshwater bath and rinsed through a 100 m strainer (Bull and Mitchell, 2002, p45). Juvenile H. ingens are ready to be weaned onto frozen mysids by the age of 8 weeks. Jorge finds it helpful to leave the frozen mysids unenriched during this initial training period. He feels the juveniles can better recognize the frozen mysids as prey if it free of any enrichment coating (Bull and Mitchell, 2002, p45).

Juvenile H. ingens experienced occasional problems with gas bubble syndrome and secondary Vibrio infections (i.e., the Gram Negative bacteria Vibrio alginolyticus). Feeding the antibiotic Doxicycline to the juveniles bioencapsulated in Artemia franciscana nauplii was found to helpful in treating the Vibrio (Bull and Mitchell, 2002, p45)

Discussion:
Hippocampus ingens are true giants among the seahorses. They can reach a length of 36 cm or more than 14 inches when fully grown, making them the world’s largest seahorses, rivaled only by the biggest examples of H. abdominalis. The prehensile tail of a large adult has a powerful grip like an anaconda, and they can exert enough pressure to leave you counting your fingers afterwards when they squeeze down.

But despite their great size and power, these gentle giants are not at all the brutes you might imagine. As Alisa Abbott points out, they are close relatives of the Brazilian seahorse (H. reidi), and share their slender profile and graceful proportions (Abbott 2003). Imagine a seahorse with the same sleek silhouette as reidi, but which reaches twice their size, and you will have a pretty good picture of what H. ingens is like (Abbott 2003). They are stately steeds, built like thoroughbred racehorses, which carry their size very well. The crowning touch for the King of all the seahorses is a tall, backward-swept, five-pointed coronet, which adds to their majestic appearance (Abbott 2003). They have very prominent eye spines but are otherwise relatively smooth bodied with small blunt spines.

The Hawaiian strain of captive-bred ingens is a bright golden yellow, often further adorned with a lacy latticework of vivid purple-to-lavender lines. The farm-raised specimens are extremely social and don’t form permanent pair bonds, whereas their wild counterparts are believed to be monogamous (Giwojna, Jun. 2002). The captive-bred giants are extremely aggressive eaters in comparison to wild-caught H. ingens, and take enriched frozen Mysis as their staple diet (Giwojna, Jun. 2002). When offered live foods, they are active hunters that prefer to chase down their prey rather than waiting for it to come to them (Eliezer Zúñiga, pers. comm.).

DNA comparisons using molecular markers (cytochrome b gene sequences from mitochondrial DNA) show that the closest relative of the eastern Pacific seahorse (H. ingens) is none other than the Brazilian seahorse (H. reidi) from the western Atlantic (Dames 2000). It’s believed that the Brazilians and ingens evolved from a single ancestral species beginning about 3 million years ago when the Isthmus of Panama was first formed (Dames 2000), forever dividing their common ancestors into an Atlantic population and a Pacific population. Over the next 3 million years, the Atlantic population developed into the ever-popular Brazilian seahorses (H. reidi), while the Pacific population continued to diverge into the gigantic H. ingens (Giwojna, Jun. 2002). The two species are still closely tied in terms of their reproductive strategy. Both species produce enormous broods (up to 2000) of tiny fry (6-7 mm long) after a short gestation period (14-15 days), leaving the fry with a prolonged pelagic phase in which to complete their early growth and development (Giwojna, Jun. 2002).

There seems to be considerable confusion regarding the temperature requirements of H. ingens. In the literature, you will often see them described as subtropical or even temperate seahorses, but the literature is quite mistaken on this point. They are truly a tropical species whose range extends into subtropical regions in some areas and occasional carries it into temperate areas such as San Diego when El Nino conditions push warm water currents unusually far north (Hubbs and Hinton 1963; Soto 1985).

Carol Cozzi-Schmarr, of the Ocean Rider seahorse farm in Hawaii, is very familiar with H. ingens from her days culturing High Health shrimp in the tropics, which extend from 7º to 23ºN and 7º to 23ºS. The seahorses in these regions were attracted to the shrimping grounds to feed on the larval crustaceans and suffered heavy losses to shrimp trawlers. In fact, it was that experience that first got her and Craig thinking about culturing High Health seahorses rather that shrimp. Here’s what Carol has to say about the temperature requirements of H. ingens (Carol Cozzi-Schmarr, Sep. 2002):

<quote> “The Pacific Sea horse (Gigante) is a very beautiful and majestic seahorse indeed! I can see why you would want to add a pair to your tank. I can also see why you are confused about their temperature requirements. Lets take a look at their natural home ranges and the corresponding ocean temperatures from which the come. This will help you to see that this sea horse is a truly tropical and highly social species!

Their geographic range extends from the coastal waters as far North as San Diego during El Nino years and as far South as the Galapagos and northern Peru. Peru is slightly south of the equator where as the Galapagos and Ecuador straddle the equator!! The ocean temperature here averages from 80F to 82F! The H. ingens’ range then extends from here up the coast along the Pacific side passing by the Western coast of Columbia (approximately 1-7 degrees latitude), Panama (approximately 7 degrees latitude), Costa Rica (approximately 8-10 degrees latitude), Nicaragua (approximately 10 degrees latitude), El Salvador (approximately 10 degrees latitude), Honduras (approximately 10 degrees latitude) and Guatemala (approximately 14-15 degrees latitude). This whole area has some of the warmest ocean waters on the planet. Warm equatorial currents flow here all year around with the average ocean coastal temperatures being between 82°F and 84°F and increasing to as high as 90°F during the summer (our winter)!! All very hot places with bathtub like ocean temperatures.

This is the main range of this species with coastal waters also being a very, very rich nursery area for Penaeid Shrimp larvae! In fact, the H. ingens (like many sea horses around the world) is a bycatch brought up by local fisherman trawling for shrimp in mostly small wooden pongas (canoe-like boats) but also in larger commercial trawlers. At one time these sea horses were so plentiful and so easy to collect that millions of H ingens were heavily harvested annually for the Chinese medicine market. Now, of course there just are not that many left.

The range now extends into Mexico with a latitude between15-20 degrees. These coastal areas are more familiar to most North Amercians from the large tourism industry. The waters here are still very warm most of the year but do start to cool during the winter with typical ranges being from 72°F to 80°F. Now we reach Baja California and San Diego (30-32 degrees latitude) where H. ingens has been occasionally seen during the El Nino years. Normally the average temperature of San Diego is a chilling range of 55°F to 65°F (13°C-18.5°C) with the warmer temperatures lasting a few brief months in August and September. During El Nino years the warmer currents that originate off equatorial Ecuador push further north than normal bringing the high temp up to as high as 72°F to 75°F (22°C-24°C)!! This happens on the average once every 4 years. It is during these brief moments that the Pacific Sea Horse has been seen in southern California. There may even have been and occasional sighting further North but this is not their typical home range.

Now it is true that sea horses have an amazing ability to adapt to temperatures different from their native waters, although that may affect their color, activity level and general health and longevity. The Pacific Sea horse (and many other species as well) is one that has adapted fine to these cooler temperatures.

The reason that Public Aquariums use cooler water is simple…it costs a lot of money to heat saltwater especially when using high volumes like most Aquariums do. If the species in question can adapt well to cooler temperatures and it does not adversely affect the health of the animal this is not a problem. It saves the aquarium a lot of money.

Most Aquariums around the world are located in temperate areas where the ambient ocean temperature from which they pump their water is around 50°F to 55°F (10°C-13°C) or cooler!! They just cannot afford to heat water at all or any more than absolutely necessary. Adjusting the temperature in any way different from the ambient sea from which they pump their seawater if they are lucky enough to be on the coast is an expensive proposition. If they are located far away from the coast and must make their own seawater the cost of heating is an extra expense that adds to an already highly costly recirculation process.

For the home aquarist the situation is the reverse. It is extremely expensive for the hobbyist to cool seawater. It is least expensive to keep your tank at your house ambient temperature, which for most of us is about 75°F or to heat a little bit up to 78°F with a simple heater during the winter months.

So you can put the Pacific Sea Horse in a cooler tank (60°F-65°F) with a chiller if you want to after a very, very careful and slow acclimation but it is not their ideal temperature as they are not temperate fish. You will not see their magical colors and they will be much less active than normal. These Gigante sea horses are true tropical dwellers! Not only do they like it warm but they have big appetites and they are very social!! You will see beautiful tropical colors and a truly happy and active sea horse if you can keep them in herds and at temperatures from 75°F to 80°F (24°C-26.5°C)!! There is no need for a chiller, that is for sure!! Aloha, Carol” <end quote> (Carol Cozzi-Schmarr, Sep. 2002)

All things considered, I would say the comfort range for H. ingens in the home hobby tank falls between 72°F-78ºF (22°C-25ºC), with 74°F-76ºF (23°C-24ºC) being optimal. The captive-bred H. ingens from Hawaii are raised at a constant 75ºF (24ºC) and that is the temperature the ingens keeper should aim to achieve. Aquarium temperatures must be kept below 84°F-86ºF (29°C-30ºC), which can cause fatal heat stress in H. ingens (Eliezer Zúñiga, pers. comm.). Likewise, temperatures below 68ºF (20ºC) should be avoided because the activity of ingens slows to a standstill at such cool temperatures (Eliezer Zúñiga, pers. comm.).

The Hawaiian strain of H. ingens is typically shipped at about 6 inches in length and becomes sexually mature at 10-12 months — about twice as long as it takes most large seahorses to mature. That means the young adults you receive will do just fine in a standard, off-the-shelf aquarium of 30-50 gallons for at least the first year or so. As they reach their full adult growth, you may eventually need to move them into large quarters. An aquarium at least 28 inches deep is recommended for best results. (Jorge Gomezjurado suggests a tank over 1 meter deep for the large public aquaria that display H. ingens.)

Besides the strain of H. ingens raised at the renowned seahorse farm in Hawaii, a Mexican strain of captive-bred ingens has recently become available in the US. Hobbyists experienced disappointing results with the Mexican ingens at first, experiencing many losses, until it was finally realized they needed to be kept by themselves in a species-only tank. The Mexican ingens that were kept with other fishes — even other types of captive-bred seahorses — fared very poorly, while the Mexican ingens that were kept by themselves did just fine. Keep this in mind if you obtain the Mexican strain. They deserve to be kept in a species-only tank all their own.

In the wild, H. ingens has become becomes increasingly threatened due mainly to over-fishing and habitat loss. Large, smooth-bodied seahorses in general are much sought after for Asian folk medicine because of their supposed curative powers for many illnesses, and H. ingens are especially prized due to their exceptional size. They are dried by the ton and ground into powder so they can be mixed into folk medicines and potions to treat everything from baldness to infertility.

As a result, wild populations have declined dramatically in the last decade and are now in serious trouble. Sadly, this species is much favored for Traditional Chinese Medicine (TCM) and very vulnerable to exploitation by various commercial fishing operations in the eastern Pacific (Mann, 1998). These giant seahorses are often harvested by Ecuadorian fishermen trawling for shrimp, who retain them as a welcome source of added income and sell them on the world market as a key ingredient in Asian folk medicines (Giwojna, Jun. 2002). The seahorses are irresistibly drawn to the shrimping grounds, where they concentrate to feed on the larval shrimp, and ingens populations were quickly decimated once the fisherman realized that fact and began specifically targeting the seahorses (Giwojna, Jun. 2002).

Ecuadorian government records show that between 1983 and 1995 alone, the country exported almost four tons of dried Hippocampus ingens, mainly to Taiwan (Mann, 1998). When you consider that a dried specimen literally feels light as a feather, four tons worth represents an awful lot of dried seahorses (Giwojna, Jun. 2002)! Nor does that total include the additional live specimens that were exported for the ornamental fish industry.

And that is just the take by a single country from only one of the remaining Hippocampus ingens strongholds (Giwojna, Jun. 2002). Although the exact figures are not available, you can be certain that the fisheries from other seafaring nations in the region have taken a similar toll from the H. ingens habitat clusters in their vicinities. For instance, Costa Rica is a major shippper of ingens, as were Nicaragua, Honduras and Mexico until the seahorses declined dramatically in their waters (Carol Cozzi-Schmarr, pers. comm.). Mexico and the Galapagos now strictly protect their ingens remnants, but Costa Rica still does not.

As a result of such over harvesting, H. ingens has disappeared from vast areas of its former range, leaving remnant populations scattered over a large area. Nine ingens strongholds now remain scattered from Baja, Mexico to Peru, but these isolated population pockets are at risk from habitat destruction and overfishing (Giwojna, Jun. 2002). The triple threat posed by its patchy distribution within highly endangered ecosystems, overfishing, and the specter of TCM has painted a bleak picture for the prospects of wild ingens populations (Giwojna, Jun. 2002).

Consequently, the World Conservation Union officially placed Hippocampus ingens on the Red List of Threatened Species in 2000, predicting a further decline of over 20% in their numbers within three generations, a grim forecast that also applies to the Brazilian seahorse, which is likewise categorized as “vulnerable” on the Red List (IUCN 2000). The successful breeding and rearing programs for H. ingens developed by Carol Cozzi-Schmarr in Hawaii, Jorge Gomezjurado at the National Aquarium in Baltimore, and Eliezer Zúñiga V in Mazatlan, Mexico are a very welcome development and a badly needed life insurance policy for these titans of the Pacific. Prior to their pioneering efforts, the best survival rates achieved for this hard-to-raise species were a meager 7%-8%, with a dismal 1% juvenile survival rate being the norm (Mann, 1998).

Bottom Line:
Hippocampus ingens is not quite as hardy as some of the other captive-bred species that have been farm-raised for more generations and achieved a greater level of domestication, and for this reason I don’t recommend H. ingens for beginners. Nor is this seahorse a good candidate for hobbyists who want to raise their seahorses and try their hand at home culture.

However, these impressive animals are magnificent specimens for the experienced seahorse keeper. Given their preference for gorgonians on patch reefs, H. ingens is also a good option for modified reef tanks. Otherwise, they’re best-suited for large species-only tanks — especially if you are considering the Mexican strain of captive-bred H. ingens!

©Copyright 2009. All rights reserved. Permission to reproduce is granted by the author (Peter Giwojna) for your personal use only and is not transferable without written permission by Ocean Rider and the original author.

Additional Information (to learn more about Hippocampus ingens, please consult the following references):

Fritzsche, R.A. 1980. “Revision of the eastern Pacific Syngnathidae (Pisces: Syngnathiformes), including both recent and fossil forms.” Proceedings of the California Academy of Sciences 42(6): 181-227.

Gomezjurado, J. 1998. ‘The biology and husbandry of the Pacific giant seahorse, Hippocampus ingens: A conservation project at the Steinhart Aquarium. AZA Conference Proceedings.

Groves, J.S. and R.J. Lavenberg. 1997. The fishes of Galapagos Island. Stanford University Press. California.

Hippocampus ingens, Pacific seahorse. 28 Feb. 2004. Fish Base.
http://www.fishbase.org/Summary/SpeciesSummary.cfm?id=3284

Hubbs, C.L. & S.D. Hinton. 1963. “The giant seahorse returns.” Pac. Disc.16(5): 12-15.

Jones, A. T., P. Dutton, & R.E. Snodgrass. 1988. “Reoccurrence of the Pacific seahorse Hippocampus ingens, in San Diego Bay.” Calif. Fish and Game 74(4): 236-248.

Mann, Robert H. 1998. Guiding Giant Seahorses. California Wild – Academy Seahorse Project. [Online] Available at: <http://www.calacademy.org/calwild/archives/seahorse.htm&gt;

Okay, TJ, that’s the rundown on the Ocean Rider strain of Hippocampus ingens.

Best wishes with all your fishes!

Happy Trails!
Pete Giwojna