Re:lying on bottom

Pete Giwojna

Dear Scubagal:

I’m sorry to hear that you’re female seahorse is having problems. It sounds like your seahorse is suffering from negative buoyancy and/or generalized weakness, but it’s very difficult to say why she may be having such problems. The type of behavior you describe — great difficulty in swimming, laying horizontally on the bottom, and the inability to assume his 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 a swim bladder disorder or a buildup of fluid accumulating within the coelomic cavity or abdomen.

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. However, this is a gradual process and may take days to accomplish.

But 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, which sometimes also contribute to generalized weakness, so I think it it would be prudent to isolate the seahorse in a hospital tank in case it has something that is contagious and then treat her with a good antiparasitic that is effective against internal parasites, such as metronidazole or praziquantel.

Metronidazole is an antibiotic with antiprotozoal properties that is very effective in eradicating internal parasites in general and intestinal flagellates in particular (Kaptur, 2004). It is ideal for this because it is rapidly absorbed from the GI tract, has anti-inflammatory effects in the bowel, and was designed specifically to treat protozoal infections and anaerobic bacterial infections by disrupting their DNA (Kaptur, 2004).

If the seahorse is still eating, administering the metronidazole orally via gut-loaded shrimp is often extremely effective (Giwojna, Dec. 2003). Keep the seahorses on a strict diet of gut-loaded brine shrimp for 5-10 days. When administered properly, metronidazole is wonderfully effective at eliminating intestinal parasites, and there should be signs of improvement within 3 days of treatment (Kaptur, 2004).

Gutloading simply means to fill live shrimp up with medication by feeding them food that’s been soaked in the desired medication. Once the feeder shrimp are full of the medicated food — that is, their guts are loaded with it — they are immediately fed to the seahorses, which thus consume the medication along with the shrimp. It’s a neat way to trick seahorses into taking their medicine, just as our moms used to do when were little, crushing up pills in a spoonful of jelly or jam. Another term for gutloading is bioencapsulation, since the medication is neatly contained within a living organism rather than a capsule. Gutloading allows the seahorses to be treated in their main tank, where they are completely at home, surrounded by their tankmates and the rest of the herd, and is thus a very stress-free form of treatment.

There are a number of ways to gutload shrimp, but many hobbyists find it easiest to gutload adult brine shrimp with metronidazole as described below. It is impossible to determine precisely what dosage of medication each individual fish ingests when gutloading, but metronidazole is a very, very safe drug and you cannot overdose a seahorse using this method of treatment. Feeding each seahorse its fill of shrimp gut-loaded with metronidazole for 5-10 days assures that they receive an effective dose of the medication.

Adult brine shrimp can gut-loaded or bio-encapsulated as follows. To medicate the brine shrimp, dissolve approximately 100 mg of metronidazole per liter or about 400 mg per gallon of water and soak the shrimp in the resulting freshwater solution. If the metronidazole you are using comes in liquid or capsule form, you can use it as is. But if the metronidazole is in tablet form, be sure to crush it into a very fine powder (you may have to use a household blender to get it fine enough) and dissolve it in freshwater at the dosage suggested above. Soak the adult shrimp in freshwater treated with the antibiotic for 15-30 minutes and then feed the medicated shrimp to your seahorses immediately. (Don’t let your pumps and filters "eat" all the brine shrimp!)

The brine shrimp are soaked in freshwater, not saltwater, because in theory the increased osmotic pressure of the freshwater helps the antibiotic solution move into their bodies via osmosis. But in fact nobody knows for sure whether the antibiotic is diffusing into the brine shrimp or they are ingesting it in very fine particles (brine shrimp are filter feeders and will take in whatever is suspended in the water with them) or whether the brine shrimp merely become coated with the antibiotic while they are soaking in it. But that’s not important — all that really matters is that gut-loading adult brine shrimp with medications this way is effective.

Keep the seahorses on a strict diet of such medicated brine shrimp throughout the treatment period to get as much of the antibiotic into the seahorses as possible, and mix up a new batch of medicated freshwater to soak the brine shrimp in for each feeding.

You should be able to obtain a medication at your local fish store that has metronidazole as all as its primary ingredient, Scubagal. Administering it to your seahorses via gut-loaded adult brine shrimp is a very safe, gentle treatment, that should not stress your seahorses in any way. If your seahorse’s underinflated swim bladder is due to internal parasites or anaerobic bacteria, the metronidazole may help. Or she may be able to reinflate her swimbladder and restore neutral buoyancy on her own over a period of days.

If the seahorse is not eating, then treatment with praziquantel would be a better option. Praziquantel and metronidazole can be obtained from the following sources:

Click here: Fish Medications

In short, I would recommend isolating the sick seahorse, treating her with a good antiparasitic such as praziquantel or metronidazole, and then concentrating on restoring optimum water quality in your main tank, Scubagal. Perform a water change along with a judicious aquarium cleaning and hope your seahorse responds to the medication or is able to reinflate its swimbladder on its own.

Best of luck resolving this problem, Scubagal.

Pete Giwojna

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