Re:Swollen belly in female

Pete Giwojna

Dear Pat:

The only time we normally see a female seahorse with a distended abdomen is immediately after she has hydrated or ripened a clutch of eggs prior to mating, as discussed below.

Seahorses are fractional spawners and very well adapted for producing clutch after clutch of eggs. Females maintain a spiraling assembly line of developing oocytes (egg cells) at all times, only a portion of which are fully mature and are released at each mating (Vincent, 1990). This differs from the reproductive strategy of most fishes, which are multiple spawners that release all their eggs each time they mate and then start over, maturing an entirely new clutch of eggs from scratch for the next spawning.

The structure of the ovaries is unique to syngnathids. They are paired organs, which join to form a single oviduct (the seahorse’s version of a Fallopian tube) just before the urogential pore (Vincent, 1990). Oocytes spiral out from the center of each ovary, creating a coiled sheet of developing eggs at differing stages of growth (Vincent, 1990). The earliest or primordial eggs arise from the germinal ridge that runs the entire length of the ovary, and lie at the center of the coil from which they spiral out as they develop so that the fully mature eggs are the furthest from the center of rotation (Vincent, 1990). Roughly 20-25% of the outermost eggs in this ovarian assembly line are mature, ready to be discharged during ovulation and deposited with the male (Vincent, 1990). Thus, fully 70-75% of the female’s developing eggs are retained in the ovaries after mating, so a new clutch of eggs will mature relatively quickly and lie in readiness for the next mating cycle.

Seahorse ovaries are always active, busy creating and developing new eggs (oogenesis), forming the yolk (vitellogenesis), and resorbing any mature ova (atresia) leftover after mating or at the end of the breeding season (Vincent, 1990). Eggs in all 4 stages of development can be found in the ovaries throughout the year.

The mature are normally hydrated in the latter stages of courtship, shortly before the copulatory rise and transfer of the eggs that culminates the mating process in seahorses. So it would be unusual for a female to retain hydrated eggs for more than a day or so — ordinarily, if a receptive male is not available to receive the eggs, the female will simply eject them and unceremoniously dump her clutch of eggs on the bottom of the tank.

Since that has not happened in this case, there is a possibility that your female Sunburst may have become egg bound, Pat. Does she have a mate? If so, have you noticed an increase in courtship activities or increased interaction between the pair recently? Is your aquarium tall enough for them to accomplish the copulatory rise?

More information regarding egg binding and a possible treatment for the condition are discussed in the following excerpt from my new book (Complete Guide to the Greater Seahorses in the Aquarium, unpublished):

Egg Binding: a Health Risk for Breeding Females.

<quote> Egg binding occurs when a female has ripened (hydrated) a clutch of eggs and is unable to deposit them with a mate or release them for some reason. As more eggs develop, the egg bound female becomes increasing bloated and great pressure begins to build up internally. The abdomen will be very swollen, especially around the vent, and often prolapsed tissue or other material will begin to protrude from the vent as the pressure builds. The affected female will show rapid respiration and may go off her feed. If the pressure cannot be relieved, death results.

Tracy Warland describes a typical case in a female Potbelly (Hippocampus abdominalis) as follows: "Went into the shed one morning to find an adult mare, probably fully mature, in distress. She had been living quite happily in the main tank with about 10 males to meet any desire she might have. Anyway she was lying on the bottom of the tank, panting. I removed her immediately and placed her in sick tank, thought it could be parasites so gave her several 5-minute freshwater baths, but these did not seem to help. I had checked all parameters of large tank the day before so I knew the water was pristine, no other horse was stressed.

When I was putting her back after a freshwater bath, I was supporting her upright for a few minutes to see if she could hitch somewhere. I applied very slight pressure to her belly, and out shot masses of orange stuff. I collected some and checked under the microscope and it looked very much like roe, but the yolk was almost smashed, with globules of a fat-like substance within the centre. We’ve had roe before, due to unsuccessful egg transfer, so we picked up some of bottom of tank and checked it out! I put it down to women’s problems, egg bound, could not discharge unfertilized eggs, these became rotten within her and therefore caused perhaps fever like symptoms."

Egg binding is uncommon in seahorses. Most females have no problem simply dumping their eggs and spilling them on the bottom when a receptive male is unavailable. But there are two circumstances that sometimes promote egg binding. One of them is when breeding seahorses are kept in a tank that’s too shallow. Courtship will proceed normally and the female will hydrate her clutch of eggs in due course, but the pair will then be unable to complete the copulatory rise due to the lack of depth. In such a situation, the female is very reluctant too dump her eggs while a receptive male is standing by, eager to receive them. If she retains the ripened eggs too long in hope that they will be able to complete the egg transfer despite the inadequate vertical swimming space, she may become egg bound.

The other situation that may predispose females to egg binding is when the sexes are segregated. For example, Heather Hall reports that the London Zoo was so successful in breeding and raising the prolific Cape Seahorse (Hippocampus capensis) that, at one point, they were forced to separate the males and females in order to bring a halt to the population explosion that resulted (Bull and Mitchell, 2002, p 30). However, they were soon forced to abandon their experiment in enforced abstinence because it proved stressful to the seahorses and the isolated females began developing swollen abdomens and experiencing difficulty with egg binding when deprived of the opportunity to breed (Bull and Mitchell, 2002, p 30).

There is no ready cure for egg binding and attempts to manually massage the eggs from the body usually only result in internal injuries. However, there is a folk remedy that’s commonly used to treat egg binding in freshwater fish. This treatment consists of placing the affected fish in a bath of Epsom salts (magnesium sulfate) for 10-15 minutes at a dosage of one tablespoon of Epsom salt for every one-gallon of water (Duedall, 2004). The Epsom baths are repeated once a day until the patient recovers (Duedall, 2004).

I have no idea if this remedy would have any affect on a marine fish, but many freshwater hobbyists swear by it, and egg binding is fatal if unresolved so you really have nothing to lose by trying it. Epsom salts are certainly inexpensive and readily available. If you want to give it a go, I suggest administering a 10-15 minute freshwater bath with one tablespoon of magnesium sulfate per gallon added to the bath water. Mix in the magnesium salts thoroughly, aerate the container, and observe the usual precautions for any freshwater dip. Repeat once daily as needed.

As always, prevention is the best cure. If you provide your seahorses with a reasonably tall aquarium and avoid separating the males from the females, there is a very good chance you will never see a case of egg binding. <end quote>

In short, Pat, if your female’s abdomen appears swollen, particularly around the area of the vent, then I suspect that she may be egg bound. The prognosis is poor in such cases, but the condition is not at all contagious and no pathogens of any sort are usually involved, so the rest of your herd should remain unaffected.

Prolapses will often repair themselves once the internal pressure has been relieved, so if you can induce your female to release her clutch of eggs, possibly using the Epsom salts as described above, there is a chance that she may recover. The chances of a good outcome are slim once the pressure from egg binding has reached a point where tissue and compressed ova begin to extrude through the vent, but it doesn’t sound as if your female Sunburst has reached that point yet. To give you an idea of how much pressure can build up in these cases, a female will often lose 30% of her weight when she drops a clutch of eggs or transfers her ripened eggs to a receptive male.

One other possibility is that your female Sunburst may have become constipated, Pat, particularly if she is eating the frozen Mysis well twice a day but is no longer producing fecal pellets as she normally would follow me in a good feeding.

Constipation is more common in fishes with laterally compressed bodies such as seahorses and can be caused by overfeeding, a change in diet, certain medications, stress,
and rarely an intestinal blockage. The most obvious indication of constipation is an obviously swollen abdomen, particularly in the area of the vent, accompanied by a lack of fecal pellets.

The following cures for constipated fish are often suggested, but I
have no idea if they would be effective for seahorses:

(1) Fast the fish for two days.
(2) After fasting, feed the affected fish with live foods such as brine
shrimp rather than frozen foods.
(3) Soak the fish’s food in cod liver oil or place two drops of cod
liver oil directly in the fishes mouth so that it is swallowed.
(4) induce the fish to eat a single grain of Epsom salt.

Here’s what I would recommend if, you can confirm that your female is indeed constipated, Pat:

Stop feeding the seahorse immediately. Fast her for two days and
observe her closely to see if the constipation is relieved and she
produces any fecal pellets.

While she is fasting, obtain some live adult brine shrimp and cod liver
oil. If she is still not producing normal fecal pellets after two days of
fasting, soak the live adult brine shrimp in water that you’ve added
cod liver oil to for 15-30 minutes, and then feed the brine shrimp that have
soaked in (and hopefully ingested) the cod liver oil immediately to
your seahorse, being careful not to overfeed. Feed her a strict diet
of cod-liver-oil-soaked brine shrimp sparingly for a couple of days and
see if that relieves her constipation.

If that doesn’t relieve the abdominal swelling and induce her to start
eliminating fecal pellets again, you could try tube feeding her with
two drops of the cod liver oil, injecting it directly into her
esophagus so it’s sure to reach her gastrointestinal tract.

Best of luck relieving the swelling in your female’s abdomen, Pat. Here’s hoping that she soon crops her clutch of eggs and/or begins eliminating normal fecal pellets again.

Pete Giwojna

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