To Pair or not to Pair?

Dear Kimmi:

Segregating the sexes and maintaining same-sex tanks to prevent breeding can be stressful under certain circumstances. For instance, it is never advisable to separate pair-bonded seahorses and it is problematic to separate tropical species that are accustomed to breeding year-round. Separating males and females works best with temperate seahorses that have not bonded with a mate, since they are accustomed to taking a break from breeding during the off-season in any case and you will be breaking up established pairs.

In short, maintaining a same-sex seahorse tank works best with juvenile seahorses from temperate species and should generally be avoided with tropical species or seahorses that have pair bonded. Segregating the sexes is therefore a viable option with unpaired juvenile or subadult Mustangs and Sunbursts (Hippocampus erectus), but I wouldn’t recommend it for tropical species such as H. reidi, H. kuda, or H. barbouri.

So although it isn’t necessary to keep seahorses in pairs, I do feel that seahorses are happier and healthier if they have a chance to court and breed, which I think is just as true for us seahorse keepers as it is for our charges. Maintaining seahorses in pairs doesn’t necessarily mean that you must be prepared for the challenge of raising the young, Kimmi. Many times seahorses don’t immediately set up housekeeping and begin breeding in a home hobby tank. It may be many months or years before your pairs produce their first brood, and when they do begin breeding regularly, there are other options for the newborns rather than raising them yourself, as discussed below.

Many hobbyists share your concerns about breeding, Kimmi. It’s such a common quandary for seahorse keepers that I devoted a section of my new book (Complete Guide to the Greater Seahorses in the Aquarium, unpublished) to that very topic:

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To Breed or Not to Breed? That is the question…

Many seahorse keepers are unable to provide the time and effort rearing requires, particularly since a breeding pair often produces a new brood of babies (hundreds of fry) every month. When they find themselves in that situation, some hobbyists choose to prevent their seahorses from breeding by segregating the sexes and keeping males and females in separate tanks, or by ordering seahorses that are all the same gender.

Others allow their seahorses to breed, which gives the aquarist a chance to observe their amazing courtship displays and mating rituals, as well the miraculous spectacle of the male seahorse giving birth, but sacrifice the newborn fry by allowing hungry tankmates (compatible fishes and inverts, such as cleaner shrimp or scooter blennies, not the other seahorses) to make a meal of them. It sounds heartless and cruel, I know, but that’s precisely the fate most seahorse fry suffer in the ocean. At very best, only one or two seahorses from each brood survive to maturity in the wild; the rest are lost to predators.

Most people feel the parents are much happier in the aquarium if allowed to pair off and mate, so when aquarists are too busy or inexperienced for rearing fry, most hobbyists simply let nature take its course and eliminate the newborns as forage for bigger fish.

In my opinion, the deciding factor is that we now have considerable evidence that segregating the sexes can actually be harmful to the health of Hippocampus. The Cape seahorse (Hippocampus capensis) is a prolific breeder that produces well-developed benthic fry that are fairly easy to raise. So much so, in fact, that experienced breeders sometimes find themselves overwhelmed by a population explosion of capensis. When this happened at the London Zoo, the curators decided to resort to enforced abstinence as a means of population control (Bull and Mitchell, 2002, p 30). They achieved this goal by isolating their adult capensis in same-sex groups. However, they soon began to notice serious stress-related problems with this arrangement (Bull and Mitchell, 2002, p 30). There was an increase in disease outbreaks and heightened aggression among their groups of males (Bull and Mitchell, 2002, p 30). The isolated females developed swollen abdomens and experienced difficulty with egg binding (Bull and Mitchell, 2002, p 30). Respiration rates increased and there was noticeably more twitching among the segregated seahorses (Bull and Mitchell, 2002, p 30). As a result, the Zoo soon stopped separating their males and females. They are now allowed to court and breed freely and the resulting offspring are simply left in the main tank with their parents and allowed to fend for themselves (Bull and Mitchell, 2002, p 30). Some of the exceptionally hardy capensis fry manage to make it on their own and reach adulthood without any special care at all (Bull and Mitchell, 2002, p 30).

In many cases, I feel that’s the best solution for the home aquarist as well, both for the seahorses and their keepers. The seahorses certainly enjoy a richer, more natural life when they have the opportunity to interact, court one another, pair up and reproduce. And the hobbyist has a chance to observe social interactions and behaviors he would otherwise never see, such as competition for mates and daily greetings and birthing, including one of the grandest spectacles in all of nature — the colorful courtship and mating ritual of the seahorse!

Over a period of days, the partners perform a series of ritualized maneuvers and distinct displays — brightening, reciprocal quivering, pumping, pointing, and several delightful dancelike displays (the carousel dance, Maypole dance, and the parallel promenade) — all culminating in the copulatory rise and exchange of eggs. Once a pair has bonded, these maneuvers are repeated regularly in a daily greeting ritual that strengthens and reinforces the pair bond. In my opinion, the seahorses have a better quality of life when they are allowed to engage in these activities in the aquarium, even if it means sacrificing their young.

Some hobbyists have a friend or neighbor or know a fish guy from the local pet shop who are interested in rearing, and allow them to take home their seahorse fry and raise them. Some hobbyists even ship the fry to breeders elsewhere who are set up for rearing. Those are other possibilities the overburdened home hobbyist can explore.

Allowing the seahorses to breed freely leaves the door open for aquarist to try his hand at rearing someday when he’s better prepared and equal to the task. Once the hobbyist gains a little more experience and confidence keeping seahorses, there will likely come a time when the aquarist feels he’s ready for the challenge of rearing. Sooner or later, most seahorse keepers decide to try their hand at rearing. This way, when that day arrives, a breeding pair of ponies will already be at hand, ready to give their owner plenty of fry to raise. <Close quote>

So I would be inclined to order pairs, and if they promptly produce young that you are not prepared to raise, feel free to disperse the newborns to other aquarists who may be interested up until the fry are a month old. Otherwise, you can always keep a group of decorative shrimp (fire shrimp, peppermint shrimp, Scarlet cleaner shrimp, etc.) with your seahorses and allow them to intervene the natural way. As heartless as that seems, it is a natural process and a very common occurrence in both freshwater and marine aquaria. For instance, it’s not really any different than when a guppy or black mollie gives birth in a community tank, and the angelfish or adult mollies and swordtails scarf up the newborns as fast as they are delivered. For that matter, it’s not much different than when the hermaphroditic peppermint shrimp or cleaner shrimp release their larvae and the seahorses happily feast on the larval shrimp.

On the other hand, no one here is going to fault you at all if you want to set up your new aquarium with nothing but female (or male) Hippocampus kuda. But I wouldn’t recommend keeping just a single seahorse. Seahorses are highly social animals that very much enjoy the company of others of their kind. In nature, the typical social unit for many species is the mated pair, whereas others are colonial and congregate in small groups and loose assemblages. Captive bred and raised seahorses in particular are highly gregarious and are accustomed to living in close contact with other seahorses.

Best wishes with all your fishes, Kimmi! My best advice to you would be to get a male/female pair and simply enjoy the complex social interactions and fascinating behaviors of your seahorses and don’t worry if you’re not prepared for rearing any fry at this time.

Respectfully,
Pete Giwojna