Re:Do I need more than one

Pete Giwojna

Dear lilred:

You’re very welcome!

Sexing adult, fully mature seahorses in breeding condition is normally simple and straightforward — the males have a brood pouch slung under their abdomens at the base of their tails and the females do not. This difference will be most obvious when the seahorses are courting and breeding, since the stallions perform vigorous pouch displays in which they inflate their pouches with water to the bursting point, making them unmistakable.

In the off-season, however, when the seahorses are not actively breeding, it sometimes becomes difficult to tell male from female because the male’s pouch may shrink to almost nothing at this time and will not not become obvious again until hormonal changes triggered by courtship and mating cause it to grow and expand (Bull and Mitchell, 2002).

There is also a noticeable difference in the profile of the abdomen. In females, the abdomen curves inward more sharply, so that the base of the belly almost forms a right angle to the tail. In males, the abdomen slopes inward toward the tail more gently, giving the base of the belly a more rounded appearance in profile. In addition, in some species, the anal fin tends to be pointed in females and rounded in males. One can attempt to sex adolescents or even seahorse fry according to these subtle differences, but the younger the specimen, the more likely mistakes are to be made and the greater the chances that the gender that is assigned will prove to be wrong.

You can also attempt to sex immature seahorses with no indications of an incipient pouch using the position of the anal fin and a few other subtle indicators as a guide, but again, the younger the seahorses are the more difficult this is to accomplish with any degree of accuracy. Suffice it to say, sexing juvenile seahorses that are much younger than 5 months can be a very challenging adventure. This is typically done by noting the position and shape of the anal fin as well as the curvature of the abdomen. In immature females, the anal fin is situated right at the very base of the abdomen where it meets the tail and points more or less straight downward, almost flush up against the tail. In immature males that lack a brood pouch, the anal fin is located higher up on the abdomen, allowing room for the brood pouch to subsequently develop, and protrudes outward at an angle from the tail. This makes it appear as if there is more space between the tail and anal fin in juvenile males.

The difference in the position of the anal fin is due to the way the vent is situated in males and females. The seahorse’s vent is the cleft formed by the combined openings of the anus and urogenital pore (Seahorse Anatomy, 2004). It is the simple recessed passage located just above (cranial to) the anal fin in females; in males, the anal fin is located in the middle of the vent where it separates the anal opening from the urogenital pore. The male’s anus is therefore situated above the anal fin while the genital opening of the male is located below the anal fin at the mouth of the brood pouch. In females, however, both the anus and the urogenital pore are located above the anal fin.

As I mentioned in my previous post, captive-bred-and-raised Hippocampus kelloggi are new to the hobby and not a great deal is known about them at this point. Here is all of the information I’ve been able to compile on the species based on the available literature and feedback from a number of hobbyists who keep the cultured H. kelloggi:

Hippocampus kelloggi (Lourie, Vincent and Hall, 1999)
Common name: Kellogg’s seahorse (US); Great Seahorse (Australia); Offshore Seahorse (Vietnam);.o-umi-uma (Japan)
Scientific name: Hippocampus kelloggi, Jordan & Snyder 1902
Hippocampus suezensis

Maximum size: 11+ inches (28.0 cm).

Climate: subtropical to tropical, but primarily tropical.

Red Sea and Indian Ocean: Tanzania (Zanzibar), Pakistan (Kurachei), India (Madras, Malabar);
Southeast Asia: Danang Sea, Philippines, China and Taiwan; Japan and Australia (southeast Queensland, north New South Wales, Lord Howe Island).

Meristic Counts:
Rings: 11 trunk rings + 40 tail rings (tail rings vary from 39-41).
Dorsal fin rays: 18 rays (varies from 17 -19) spanning 2 trunk rings + 1 tail ring.
Pectoral fin rays: 18 soft rays (varies from 17-19).
Snout length: 2.1 (2.0- 2.3) in head length. (The length of the snout fits into the length of the head only about 2 times. In others, this seahorse has a relatively long snout that measures about 1/2 the length of its head.)
Other distinctive characters:
Coronet: medium-high, with five short spines, and a distinctive high plate in front of the crown.
Spines: low and rounded, always blunt tipped, even in the youngest specimens which have better developed spines. Adults are relatively smooth bodied.

Key Features: a prominent cheek spine (long but rounded) that points backward slightly; a deep head with a thick snout; a slender body with a long trunk and noticeably thick rings, a long tail, and a prominent eye spy (fairly tall but rounded).

Adult height: 6-10 inches (15.0-25.0 cm).

Color and Pattern:
H. kelloggi is typically a pale seahorse with uniform coloration, often adorned with tiny white spots that coalesce to form vertical lines (Lourie at all, 1999). There is some evidence suggesting sexual dimorphism in this species, with the males being darker (brownish to black), while juveniles and females are sometimes lighter in coloration (cream or yellowish), often with pale saddles or patches (Kuiter 2000). The stallions also tend to be slimmer than the females (Coit, pers. com.)

Cultured specimens often exhibit a color pattern that is similar to H. kuda, featuring a yellowish to pale olive green background coloration sprinkled profusely with small dark spots.

This is a very slender seahorse with a long trunk, an exceptionally long tail, and a thick snout that tends to flare out at the tip (Kuiter 2000)

Natural History:
Very little is known about the life history or behavior of this large slender seahorse, except that it is primarily a deepwater seahorse (> 66 feet or 20 m deep) that is often found well offshore over soft, muddy bottoms (Kuiter 2000).

I have never worked with the species, so at the present, I cannot even tell you if it produces pelagic or benthic fry, or how long the gestation period for the species may be, but now that H. kelloggi is being cultured in large numbers, that information should be forthcoming soon.

Preferred Parameters:

Hippocampus kelloggi should do well under the same conditions as other tropical seahorses. The H. kelloggi keeper should maintain stable aquarium conditions within the following aquarium parameters:

Temperature = range 68°F to 78°F (20°C-25°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 = <20 (ideally 0-10 ppm)

Suggested Stocking Density:
When fully-grown, this is a very large seahorse with a recommended stocking density similar to other giants such as H. abdominalis and H. ingens: one adult seahorse 2-3 years old per 57 liters (15 gallons) or one pair of 6-month old young adults per 15 gallons (57 liters).


H. kelloggi can easily be confused with H. kuda, which is another large, smooth-bodied tropical seahorse with similar coloration. Upon close examination, however, it is not difficult to distinguish between the two. H. kelloggi has a slimmer body build than kuda, with a more slender profile due to its exceptionally long trunk, as well as a longer tail, and the coronets of these two species are quite different (Lisa Coit, pers. com.). The small spines that form the 5-pointed crown on H. kelloggi are nothing like the low, rounded coronet of H. kuda, which may have broad flanges and overhang at the back, but is not at all spiny.

Captive-bred-and-raised Hippocampus kelloggi have only recently become available in the US and very little is known about their behavior. Hobbyists who keep captive raised H. kelloggi tell me that they tend to be real bottom huggers that rarely perch higher up then about 4 inches above the bottom (Coit, pers. com.). Their behavior in that regard is said to be similar to the Cape seahorse (H. capensis), an estuarine species that always orients to the substrate and is notorious for its bottom-hugging behavior. I’m told that they have a big appetite and feed aggressively on frozen Mysis, and are almost fearless in the aquarium — flaunting themselves in the open, never hiding, and not at all shy or retiring (Coit, pers. com.). Although they haven’t been in the hobby long enough to draw any firm conclusions, thus far the they have proven to be hardy aquarium specimens.

When courting, H. kelloggi stallions perform the usual pouch displays (Ballooning and Pumping) in which they inflate their brood pouches with water in an effort to impress the females with the awe-inspiring dimensions of their fully inflated marsupium.

New arrivals may alarm their keepers with their propensity for performing unusual color changes, in which they exhibit pale patches in various places on their body for short periods before reverting to their normal coloration again just as suddenly (Coit, pers. com.). These lighter patches can appear almost anywhere on their body, from head to tail, and are typically not symmetrical but rather confined to one side of their body only (Coit, pers. com.). This can be disturbing to the uninitiated, since depigmentation and localized loss of coloration are often signs of potential disease problems ranging from fungal and bacterial infections to ectoparasites that attack the skin and gills. In H. kelloggi, however, these unpredictable, transitory, patchy color changes simply appear to be normal behavior.
I delete that

Best of luck with the new H. kelloggi, lilred!

Happy Trails!
Pete Giwojna

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