Breeding Seahorses

Dear Lelia:

Thanks for the update — it’s good to hear from you again and to learn that your ailing stallion recovered and went on to produce healthy offspring for you. And it’s wonderful to hear that some of his offspring are now producing babies of their own — congratulations on closing the life cycle with your seahorses! That’s a remarkable accomplishment and you should be proud of your outstanding success breeding and raising your seahorses.

It sounds like you have created a veritable seahorse paradise in your adult tanks, and that your seahorses have responded with a healthy interest in breeding and mating. There aren’t too many things you can do to slow down their rate of reproduction. It’s always traumatic when mated pairs are separated, so I wouldn’t recommend that you try segregating the males and females.

But in the wild, Hippocampus erectus normally takes a break from breeding during the off-season. As winter approaches, the decreasing water temperature and shortening day length cause hormonal changes that bring the breeding season to an end. So you might try gradually reducing the water temperature and simultaneously reducing the photoperiod in your adult tanks to see if that cools down their ardor a bit. There’s no guarantee that manipulating their environmental cues like that will produce the desired results, since domesticated seahorses often breed year-round in captivity, but it is certainly worth a try.

Otherwise, you might consider dispersing some of the broods of young to hobbyists in your neighborhood that might like to give rearing a try, or you could always let natural attrition put a stop to your population explosion, as discussed below, Lelia:

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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. But breaking up the established pairs can be stressful and lead to health problems, so it’s not a good option once seahorses have already paired up.

Other hobbyists 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>

Best of luck with your burgeoning population of seahorses, Lelia! Here’s hoping that you’re successful in slowing down their urge to reproduce and can find aquarists in your area that would love to have some of the surplus young to try their hand at rearing! Keep up the great work!

Happy Trails!
Pete Giwojna