Upside hitching for 12-24 hrs. And not during hunting

Dear Stephanie:

I am sorry to hear about the problem that your female SunFire has been experiencing. She is clearly having a problem with negative buoyancy (i.e., the tendency to sink), which can result from a number of causes, making it very difficult to determine what may be causing her buoyancy problems.

The type of behavior you describe — difficulty in swimming, hanging upside down for long periods, perhaps even laying horizontally on the bottom, and the inability to assume her normal upright posture when perched to a hitching post — could be either an indication of generalized weakness or it could be due to negative buoyancy as the result of swim bladder disease or a buildup of fluid accumulating within her brood pouch or coelomic cavity.

As in many other bony fishes, the seahorse’s gas bladder functions as a swim bladder, providing the lift needed to give them neutral buoyancy. In essence, the swim bladder is a gas-filled bag used to regulate buoyancy. Because the seahorse’s armor-plated body is quite heavy, this organ is large in Hippocampus and extends from the neck well down into the body cavity along the dorsal boundary.

When the swim bladder is inflated with just the right amount of gas, the seahorse achieves neutral buoyancy, which just means that if neither tends to rise or sink. It is thus weightless in the water, with the buoyancy from its gas bladder exactly canceling out the pull of gravity. This facilitates swimming and makes holding its body upright effortless.

But a number of things can disrupt the normal functioning of the gas bladder and the gas gland that inflates it, resulting in either too little or too much gas being secreted into the swimbladder. When too much gas is secreted into the swimbladder the seahorse becomes too buoyant. Hyperinflation of the swimbladder thus results in positive buoyancy and the tendency to float. Likewise, if too little gas is secreted into the swimbladder, exactly the opposite occurs in the seahorse becomes too heavy. Under inflating the gas bladder therefore results in negative buoyancy and the tendency to sink.

The negative buoyancy that results from an underinflated gas bladder makes it difficult for the armor-plated seahorse to swim normally, rise from the bottom, or even hold itself erect. An underinflated swim bladder is sometimes a problem a seahorse can correct on its own, as more gas is gradually secreted into the swim bladder from the gas gland. This is a gradual process and may take days to accomplish. However, if your female has had this problem for a 3 to 4 weeks, then it’s pretty clear that she is not going to be able to correct the problem on her own.

It’s using upside down due to generalized weakness, that can sometimes happen when a seahorse has been unable to eat normally for an extended period of time, sapping its strength. Or it can also be a consequence of old age, Stephanie. SunFires typically reach marketable size around 6-8 months of age, so your female was probably a least that old when you receive care, and if you have had for a few years now, she may be around 4 years old or thereabouts.

So it could well be that your female is simply reaching the end of her natural life span, Stephanie. Certainly the aging process is always associated with increased morbidity and mortality, and seahorses are no exception to be sure. As seahorses age, they become increasingly vulnerable to certain conditions that did not trouble them when they were younger. This often manifests itself as an increased incidence of gas bubble disease (particularly pouch emphysema and subcutaneous emphysema), chronic wasting, and certain types of cancers. For example, I know of several older seahorses that developed malignant neoplasms, including tumors of the small intestine with liver metastasis and a case of a fibrosarcoma of the pouch. Specimens with anorexia and chronic wasting often have distended gall bladders, fatty livers, and sunken eyes. These types of age-related conditions don’t kill suddenly; rather, they debilitate the seahorse over time and it eventually succumbs to disease in its weakened condition.

Hepatic lipidosis in the most common of these age-related conditions. Of all the necropsies Dr. Martin Belli has performed on hobbyist’s seahorses, fully 38% of them had fatty livers (Belli, per. com.).

In my experience, the lifespan of 3-5 years is fairly average for captive-bred-and-raised seahorses in a home aquarist’s tank, Stephanie, so if your female SunFire is around four years old now, it’s quite conceivable that she could be suffering from hepatic lipidosis, impaired renal function, or other age-related conditions and is basically just worn down, on her way out. In that case, there there’s really nothing we can do about it, so let’s assume that her negative buoyancy is caused by something else.

For example, an underinflated gas bladder can also result from infection, and I have seen several cases of swim bladder disease that were associated with internal parasites (digenes), which sometimes also contribute to generalized weakness, so you may want to consider treating the affected seahorse with a good antiparasitic that is effective against internal parasites, such as metronidazole or praziquantel (more about that later in this e-mail).

On the other hand, her negative buoyancy could be associated with a buildup of fluid within the coelomic cavity, which is a problem that is commonly known as abdominal dropsy or ascites in tropical fish. If the female seahorse’s abdomen appears to be bloated or swollen and she is experiencing problems with negative buoyancy, that would seem to indicate a problem with abdominal dropsy or ascites, which would require treatment with the appropriate medication in order to resolve. (Let me know if that’s the case, Stephanie, and I will provide you with a treatment regimen that should be helpful.)

But as we have been discussing, hanging upside down for extended periods could also be an indication of generalized weakness, Stephanie. When that’s the case, the seahorse is too weak to hold itself upright in its normal posture, which can result in the sort of behavior you describe. In seahorses, this sort of generalized weakness is often associated with a lack of oxygen, which can result from insufficient levels of dissolved oxygen in the aquarium water at the bottom of the tank. Low dissolved oxygen levels and high levels of dissolved carbon dioxide can result if there is a lack of surface agitation and/or poor water circulation throughout the aquarium. Many times, this can be corrected simply by increasing the surface agitation and aeration in the aquarium in order to promote better oxygenation and facilitate more efficient gas exchange at the air/water interface.

But oxygen deprivation can also result from spikes in the ammonia or nitrite levels in the aquarium, or even excessively high levels of nitrate. When that happens, the high levels of ammonia/nitrite can convert the hemoglobin in the seahorses red blood cells into a form of the molecule (i.e., methhemoglobin) that is no longer able to transport oxygen. When that’s the case, a seahorse can be starved for oxygen even in an aquarium that has high levels of dissolved oxygen. This is a condition that can correct itself if you can simply eliminate the spike in the ammonia or nitrite levels, or reduce the levels of nitrates to <10 ppm. The best first aid measure for such a problem is to immediately transfer the seahorse into clean saltwater with zero ammonia and zero nitrite. In addition, a quick dip in concentrated methylene blue or a longer bath and less concentrated methylene blue can offer work wonders in such cases because the methylene blue is able to transform methhemoglobin back into the normal hemoglobin molecule, thereby allowing the erythrocytes to transport oxygen normally again. (Note: methylene blue can impair the biological filtration of the aquarium so it should be used as dips or baths, or administered in a hospital tank, rather than being added to the main tank.)

So I would recommend that you check your water chemistry to make sure that the ammonia, nitrite, and nitrate levels are where they should be. If there is any doubt about your water quality, Stephanie’t hesitate to perform one or more water changes to make sure that the water quality is optimal. In the meantime, it would also be advisable to increase the surface agitation and aeration in your seahorse setup in order to assure that the dissolved oxygen levels remain nice and high and that the levels of dissolved carbon dioxide remain low.

Let me know if there has been a spike in the ammonia or nitrite levels – or if the seahorse tank is experiencing excessively high levels of nitrate – and I will provide you with directions for performing a dip or bath methylene blue.

And of course her negative buoyancy can also be resolved of internal parasites (digenes) affecting their gas bladder, which sometimes also contribute to generalized weakness, so you may want to consider treating the affected seahorse with a good antiparasitic that is effective against internal parasites, such as metronidazole or praziquantel.

For example, Aquarium Pharmaceuticals makes a product called General Cure, which contains both metronidazole and Praziquantel, making it ideal for treating internal parasites. Here is some additional information about General Cure and not to use it according to directions, Stephanie:

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General Cure by Aquarium Pharmaceuticals

* Anti-parasitic fish medication rapidly treats a wide variety of parasitic diseases
* Effective fish medication for use in fresh and saltwater aquariums
* Treats diseases such as gill & skin flukes, hole-in-the-head disease, anchor worm, velvet, and fish lice.

Easy-to-use fish medication contains metronidazole and praziquantel in quick-dissolve powder form. Treats a wide variety of parasitic diseases – including velvet, anchor worm, fish lice, hole-in-the-head disease, and gill and skin flukes. Will not color water. For use in both freshwater and saltwater aquariums. Each packet doses 10 gallons. Economical 850 gram bulk jar doses up to 3,270 gallons and includes a 1 tsp scoop.
Packets
Active Ingredients: 250 mg Metronidazole and 75 mg Praziquantel per packet.
Directions for Use: For best results, remove activated carbon or filter cartridge from filter and continue aeration. For each 10 gallons (38 L) of water, empty one packet directly into aquarium. Repeat dose after 48 hours. Wait another 48 hours then change 25% of the aquarium water and add fresh activated carbon or replace filter cartridge.
This package treats up to 100 gallons. Two doses required for full course of treatment.
Diagnostic Chart
Gill & Skin Flukes: Very common fish parasites. Can be found on the gills, scales or skin. Not visible without the aid of magnification. Symptoms may include: darkening of skin, clamped fins, excess mucous. Fish may also swim erratically or become emaciated.
Hole-in-the-Head Disease: Symptoms include pitting and erosion of skin and muscle tissue around the face and side of body. Many infected fish exhibit poor appetite, weight loss and nervousness
Anchor Worm: These worms penetrate the skin and embed an anchor-like attachment into the fish. Often a thread-like appendage is all that is visible. Fish tissue is often red at the point of attachment. May be difficult to see without magnification.
Velvet: Heavy infestations cause a golden, velvety appearance or small, white spots on the sides of fish. Gill infestation may cause labored breathing and scratching on objects in the aquarium.
Fish Lice: A parasitic crustacean that can easily hide under the scales or other parts of fish. Fish lice pierce the skin, sucking blood and tissue fluids. Magnification is typically required to see fish lice.
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Metronidazole and Praziquantel won’t have any adverse effects on the beneficial bacteria that provide biological filtration for your aquarium, so they are very safe to use in a fish-only setup. However, some invertebrates can be sensitive to anti-parasitic medications, so if you have a lot of delicate live corals or feather duster worms or decorative shrimp, then you may want to administer the medications in a hospital tank or treatment tank instead of your main tank, Stephanie.

Good luck.

Respectfully,
Pete Giwojna, Ocean Rider Tech Support