Male Reidi

Dear Kelly:

Welcome to the Club and congratulation on your new brood of Hippocampus reidi babies!

It is not unusual for a pregnant male to give birth to a few babies a bit prematurely, and then temporarily suspend operations, only to deliver the rest of his brood as usual a day or two later. That seems to be what has happened in your case, but a brood of 50 would be abnormally small for a mature reidi stallion, so I suspect you are correct — it seems likely that more newborns (perhaps several hundred more) will be forthcoming shortly.

As I was discussing with Amber recently, Hippocampus reidi, the Brazilian breeding machine is the most prolific of all the seahorses (Abbott 2003). They have a well-deserved reputation for churning out brood after brood every two weeks with relentless regularity, and hold the world record for delivering ~1600 young in a single brood (anecdotal reports of broods up to 2000 fry are not uncommon)! So the festivities may just be beginning and there could be a lot more babies on the way.

In seahorses, a hormone known as fish isotocin, which is the equivalent of oxytocin in mammals, triggers parturition or giving birth (Vincent, 1990). Thus anything that stimulates excess secretion of isotocin can result in premature births, whereas anything which decreases or delays the secretion of isotocin can postpone delivery and prolong a pregnancy abnormally.

So there’s not really much a hobbyist can do to hurry things along when a stallion appears to be experiencing an extended pregnancy. Make sure his mate is present (i.e., don’t isolate the male in a paternity tank), maintain optimum water quality, keep the water temperature in the comfort zone, keep your dissolved oxygen levels high, and keep the aquarium as stress-free as possible. Other than that, Kelly, all you can do is relax, give your pregnant male plenty of peace and quiet, and let nature take its course.

If you do a search on this forum for the words "reidi rearing tips," you should find some useful suggestions for raising this challenging species.

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

Happy Trails!
Pete Giwojna, Ocean Rider Tech Support

Dear Kelly:

It’s pretty hard to quantify how much your seahorses should be eating because it depends in large extent on the size of the seahorses and of course the size of the individual Mysis they are eating, as well as a number of other factors. But I can tell you that the feeding regimen that generally works best for most captive-bred seahorses is to provide each of them with 2-7 frozen Mysis relicta twice a day, enriched with Vibrance, and then to fast your seahorses entirely once a week. In other words, your seahorses should each be eating a total of around 4-14 frozen Mysis each day, depending on the size of the seahorse and the size of the Mysis. But those are just rough guidelines and there is a lot of variation in how much Mysis healthy seahorses eat each day.

A large seahorse naturally eats more than a smaller pony. And jumbo-sized Mysis will fill up a hungry seahorse faster than smaller shrimp. So a seahorse that’s scarfing up king-sized Piscine Energetics Mysis relicta needs to eat fewer shrimp than a pony that’s dining on the tiny Hikari Mysis.

Aside from size, some of the other factors that determine how much a seahorse eats are water temperature, the age of the seahorse, and whether or not it is actively breeding at the moment. The warmer the water temperature (within the seahorse’s comfort zone), the higher its metabolism, and the more calories it needs to eat as a result. Young seahorses that are still growing rapidly typically eat more than mature seahorses that have reached their full growth. As you might expect, breeding pairs that are producing brood after brood every few weeks need to eat a lot because so much of their bodily resources go towards producing clutches of eggs or nourishing a pouch full of developing young.

So don’t get hung up trying to count every morsel every seahorse in your tank scarfs down, Kelly. Just make sure all your seahorses have full bellies at the end of the day, as indicated by their well-rounded abdomens. After a good feeding, the seahorses belly rings should be flush or even slightly convex in cross section when viewed from head on. (We never want to see sunken, severely pinched-in abdomens on our seahorses! Concave belly rings are a sure sign of an underfed seahorse, with the sole exception of a female that has just transferred her eggs.)

So if you want to check whether your seahorses are eating well or not, Kelly, don’t look at their profile — examine them head-on and check out their gut. Their abdomens or belly plates should bulge out slightly or at least be flush with their flanks, not pinched in or sunken. In other words, when viewed from the back or from head-on, the cross-section of their abdomens should appear concave "( )" or flush "l l" rather than concave ") (" or pinched in.

In general, it’s a good idea to offer one morning feeding and one mid-to-late afternoon feeding, if possible, but there are no hard-and-fast rules when it comes to easy-to-feed, farm-raised horses. Some hobbyist prefer to give their seahorses two feedings a day, while others prefer to give them their quota of frozen Mysis in one big meal. As long as they get their fill, there is really no right or wrong way to go about this — just do whatever works bests for your seahorses and your schedule.

However, many hobbyists find that their seahorses feed best during the morning, so if you can only feed your seahorses once a day, try to make it a morning meal. Whether it’s their biological clocks, something built into their natural circadian rhythm, or just that they’re simply hungriest shortly after waking up after not eating all night, seahorses do seem to feed more aggressively in the morning, and hobbyists should try to accommodate them, if possible. Breakfast, it seems, is the most important meal of the day for our aquatic equines as well as ourselves.

If you can only manage one feeding a day, DO NOT make it an evening meal. The worst thing you can do is to feed your seahorses late in the day when there will likely still be leftovers remaining at lights out. The uneaten Mysis will begin decaying overnight and put your water quality at risk. Worse still, the next morning, when they are hungriest, your seahorses may discover the bacteria-laden Mysis and snap them up off the bottom. This is an excellent way to spread disease and make your seahorses sick. Feeding your seahorses early in the day, so they have plenty of time to clean up leftovers, is a good way to prevent this. An efficient clean-up crew of scavengers also helps.

It sounds like you have worked out a very sensible feeding regimen in that regard, Kelly. It’s a good idea to give your seahorses a big feeding in the morning when they are hungriest, and then a smaller meal later in the day, which they can easily clean up before lights out.

Just be sure that you don’t scatter-feed frozen foods!. Whether it is a SHOWLR tank, a modified minireef, a seagrass system or a mangrove biotype, a well-designed seahorse setup is a fairly elaborate environment. A certain level of complexity is necessary in order to assure that our seahorses behave naturally (Topps, 1999) and to provide our ponies with plenty of hitching posts and shelter, and enough sight barriers to assure them a little privacy when they feel the need to be alone. Their homemade habitat may thus take the form of a labyrinth of live rock, an intricate arrangement of corals and gorgonians, a well-planted bed of seagrass or macroalgae, or a full-fledged reef face. When feeding seahorses in such intricate surroundings, the worst thing you can do is to scatter a handful of frozen Mysis throughout the tank to be dispersed by the currents and hope that the hungry horses can track it all down. Inevitably some of the frozen food will be swept away and lodge in isolated nooks and crannies where the seahorses cannot get it. There it will begin to decompose and impair your water quality, which is why ammonia spikes are common after a heavy feeding. Or it may be wafted out into the open again later on and eaten after it has gone bad. Either outcome can lead to dire problems.

Using a feeding station or target feeding your seahorses and diligently cleaning up any leftovers afterwards can avoid this. That is absolutely imperative when maintaining seahorses in an appropriately elaborate environment. An efficient team of aquarium janitors and scavengers can also be a big help with the tidying up.

Best of luck keeping our galloping gourmets well fed, Kelly!

Happy Trails!
Pete Giwojna

Dear Kelly:

That’s a good question regarding just how long a male seahorse can stay pregnant and still deliver a viable brewer of young. There isn’t a simple answer to that question because so many factors can influence the gestation of a gravid male, but I would be happy to share my thoughts on the matter with you for whatever it’s worth.

For starters, gestation in seahorses is largely determined by water temperature, is controlled by the levels of key hormones, and can be influenced to a lesser degree by diet and nutrition.

In general, the warmer the water the shorter the gestation period, and vice versa. (We’ll discuss how water temperatures can affect the pregnancy in more detail later in this post, Kelly.).

Aside from water temperature, gestation may vary due to hormonal influences as well. For example, in seahorses, a hormone known as fish isotocin, which is the equivalent of oxytocin in mammals, triggers parturition or giving birth. Thus anything that stimulates excess secretion of isotocin can result in premature births, whereas anything which decreases or delays the secretion of isotocin can postpone delivery and prolong a pregnancy abnormally.

In a similar manner, disruption of other hormones can cause a male to spontaneously abort a pregnancy or to actually resorb the eggs. The placenta-like changes that take place in brood pouch, the development of the embryonic young, and the pregnancy itself are all controlled by various hormones — testosterone, adrenal corticoids, prolactin, and isotocin — so basically anything that influences the secretion of those key hormones can have a profound effect on the pregnancy

Some of the factors that influence these hormonal responses are the presence of the female, low oxygen levels, diet and, of course, stress. The presence of the female most definitely influences the gestation and brood success of her mate. Numerous studies indicate that the presence of female fishes visually or hormonally stimulates male sexual activity such as courtship, nest building, and the development of androgen-dependent sexual characteristics (Vincent, 1990). Research has also shown conclusively that male seahorses which have been with the same female for more than one mating cycle are markedly more successful in brooding young (Vincent, 1990). It is believed that one of the reasons for this is that the presence of their mate stimulates the secretion of the corticoids (steroid hormones produced by the adrenal cortex) and prolactin that control the pouch environment and maintain the incubation (Vincent, 1990). The male is thought to further expand his pouch and develop the placenta-like internal structures to a greater degree as a result (Giwojna, Feb. 2002). More of the eggs can then be successfully implanted and carried to full term (Giwojna, Feb. 2002). Separating a gravid male from his mate can therefore have a negative impact on his pregnancy and should be strictly avoided.

Low oxygen levels during pregnancy can likewise be disastrous. They result in respiratory distress for the gravid male, putting the embryonic young at risk, as well as directly altering the hormones we have been discussing, which can further disrupt the pregnancy.

Poor water quality — especially ammonia and/or nitrite spikes — are one of the most common aquarium stressors that can disrupt hormones and interrupt a pregnancy. Stress hormones such as cortisol will be released in response to such stressors, at the expense of other adrenal hormones, which can have a negative impact on the pregnancy and the developing fry.

Heat stress is doubly bad news for gravid males. Not only can abnormally warm temperatures disrupt the secretion of these key hormones and shut down breeding, they can also directly denature long chain polymers and macromolecules (e.g., proteins, enzymes and hormones) by altering certain bonds and changing the three-dimensional shape of the molecule on the atomic level. And, of course, water temperature also directly affect the metabolism of the seahorse and therefore its gestation period. Up to a certain point, increasing water temperatures will shorten the normal gestation period, just as decreasing water temperature will prolong or extend gestation.

Past a certain point, however, when the increasing temperatures exceed the comfort range for the seahorses, elevated temperatures will bring reproduction to an abrupt halt. For example, 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.).

An inadequate diet can also be detrimental to a gravid male for obvious reasons. Maintaining a large brood of developing young can be a big drain on the male’s bodily resources, and a nutritious diet rich in HUFA and essential fatty acids is necessary at this time to help the male keep up his strength. That is why male seahorses have an intestinal tract that’s 50% longer than that of females (Tamaru, Aug. 2001). They need the extra food absorption ability and digestion a longer intestine provides in order to sustain the metabolic demands of up to 1600 rapidly growing fry.

So the actions of the aquarist and the aquarium conditions can have a big effect on how well a pregnancy progresses, and whether or not the fetal fry develop normally and are brought to full term, or are aborted, delivered prematurely, or resorbed as embryos. In short, Kelly, it’s important to handle Romeno with care during his pregnancy, to keep him and his mate together, and to provide him with a nutritious diet, optimal water quality, and a stress-free environment at all times.

Here’s hoping that your water change produces the desired results and Romeo delivers the rest of his brood without difficulty. It sounds like you’ve been doing a great job raising the offspring from your seahorses so far, Kelly — keep up the good work!

Happy Trails!
Pete Giwojna

Dear Kelly:

Yes, you are doing splendidly for your first attempt at rearing seahorses! The Hippocampus reidi fry are notoriously difficult to raise due to their extended pelagic phase, and you seem to be sailing along through their high-risk period quite well indeed. There’s always a steep learning curve and it’s not uncommon — perhaps even the rule — for home breeders to lose the entire brood during their first few attempts at rearing, so keep up the good work!

Best of luck keeping up with the endless appetites of all year newborns and juveniles, Kelly!

Happy Trails!
Pete Giwojna