Dear Sherry:

Pete Giwojna

Dear Sherry:

I’m sorry to hear that one of your seahorses has developed a problem, Sherry.

It sounds like your seahorse is suffering from negative buoyancy and generalized weakness, but it’s very difficult to say why he may be having such problems. The type of behavior you describe — laying 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 swim bladder disease or a buildup of fluid accumulating within his 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. 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 and can stop the seahorse from eating. Under the circumstances, I would suggest treating the affected seahorse with a good antiparasitic medication that is effective against internal parasites, such as metronidazole.

If the seahorse is still eating, administering the metronidazole orally by combining it with Seachem Focus and then mixing it with frozen Mysis you have prepared as usual it is very effective for treating a variety of internal parasites, Sherry.

If the seahorse is not eating, then you should consider treating the main tank with a good antiparasitic that is effective against internal parasites, such as metronidazole or praziquantel. Those are medications that will not be harmful to the fish or most invertebrates that are commonly used as aquarium janitors for the cleanup crew, and they will not have a harmful effect on the biological filtration, so they can be used to treat the main tank, which is probably a good idea since if this is some sort of parasite problem, the rest of the seahorses may also have been exposed.

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).

In short, if the seahorse is eating well, I would recommend feeding your seahorses with frozen Mysis that have been medicated with Seachem Metronidazole and treated with a good appetite stimulant (i.e., Seachem Focus together with Seachem Garlic Guard) for all of their feedings for the next two weeks. It is actually quite easy to treat the frozen Mysis after you have carefully thawed out the frozen Mysis as usual, Sherry, as we will discuss in more detail below:

I suggest medicating your seahorses frozen Mysis with a good antiparasitic (Seachem Metronidazole) together with an antibiotic (Seachem Focus) and then soaking them in Seachem Garlic Guard, which acts as an appetite stimulant. Your seahorses will ingest the medicated frozen Mysis and receive protection from potential bacterial and parasitic infections, which could explain the skinny seahorse’s loss of weight and suspicious coughing behavior.

The following information will explain how to use these products (Seachem Metronidazole, Seachem Focus, and Seachem Garlic Guard) properly to medicate the frozen Mysis, Sherry.

Seachem Metronidazole Aquarium Fish Medication – 100 g

Product Description:
Parasitic and Bacterial infections don’t stand a chance with Metronidazole. When you find your fish infected with such nasty bugs as Ich or Hexamita, grab the Metronidazole and say goodbye to infection. This fast and effective treatment is safe for biological filtration and is easily removed with carbon after treatment. For freshwater or marine fish.


Do not use UV, ozone or chemical filtration during use.
Use 1-2 measures (each about 100 mg each) for each 10 gallons. Measurer included. Repeat every 2 days until symptoms disappear.

To feed, blend 1 measure with about 1 tablespoon of frozen food paste.

Okay, Sherry, that’s the rundown on the Seachem Metronidazole, which comes in powder form and includes a little scoop for measuring the doses.

And here is the corresponding information for the Seachem Focus, which also comes in powder form with its own measuring scoop:

Seachem Laboratories Focus – 5 Grams Information

Focus ™ is an antibacterial polymer for internal infections of fish. It may be used alone or mixed with other medications to make them palatable to fish and greatly reduce the loss of medications to the water through diffusion. It can deliver any medication internally by binding the medication to its polymer structure. The advantage is that the fish can be medicated without contaminating the entire aquarium with medication. Fish find Focus™ appetizing and it may be fed to fish directly or mixed with frozen foods. Focus™ contains nitrofurantoin for internal bacterial infections. Marine and freshwater use. 5 gram container.

Types of Infections Treated:


DIRECTIONS: Use alone or in combination with medication of your choice in a 5:1 ratio by volume. Feed directly or blend with fresh or frozen food. Feed as usual, but no more than fish will consume. Use at every feeding for at least five days or until symptoms clear up.

Contains polymer bound nitrofurantoin.

Active ingredient: polymer bound nitrofurantoin (0.1%). This product is not a feed and
should not be fed directly. Its intended application is to assist in finding medications to fish food.

That’s the rundown on the Seachem Focus, Sherry.

Here is the corresponding information for the Seachem Garlic Guard. Please pay close attention to the directions that I have bolded for you below, since that’s precisely how you will need to use the Seachem Metronidazole and Seachem Focus with the Garlic Guard for pretreating your frozen Mysis for the next couple of weeks:

Seachem Garlic Guard

* For fresh and saltwater fish, planted and reef aquariums
* Contains allicin, the active ingredient in garlic
* Contains vitamin C for enhanced health benefits

Whet your fishes’ appetite with the natural healthful properties of garlic. Contains allicin, the active ingredient in garlic with powerful antioxidant properties that can lessen free radical damage to cells – plus ViJilln C for enhanced health benefits. For fresh and saltwater fish, planted and reef aquariums.

Directions for Use: Shake well before use. Soak food in Garlic Guard before feeding. For enhanced effectiveness against Ich and other parasites use Seachem’s Focus and Metronidazole as follows: Add 1 measure of Metronidazole to 1 measure of Focus per tablespoon of frozen food. Completely soak this food mix in Garlic Guard, refrigerate, and feed once or twice daily for 1-2 weeks.

Guaranteed Analysis
Garlic Extract 9900 ppm
Allicin 130 ppm
(active ingredient)
Vitamin C 1000 ppm

Okay, Sherry- as you can see from the information above, it is actually quite easy to medicate the seahorse’s frozen Mysis using these products: You just use one scoop of the Seachem Metronidazole and one scoop of the Seachem Focus to 1 tablespoon of frozen Mysis, gently mix the powder in with the thawed Mysis, and then thoroughly soak the resulting mixture in Seachem Garlic Guard. The medicated frozen Mysis and then be fed directly to the seahorses and any excess can be frozen for later use.

Call around to your local pet shops and fish stores to find one who carries products from Seachem Laboratories, Sherry, and they should have all of the products above. If not, they are all readily available online from many different sources and are fairly inexpensive.

If the seahorses not eating and you need to medicate the main tank, you should be able to obtain a medication at your local fish store that has metronidazole as all as its primary ingredient, Sherry. If your seahorse’s underinflated swim bladder is due to internal parasites or anaerobic bacteria, the metronidazole may help. Or he may be able to reinflate are swimbladder and restore neutral buoyancy on his own over a period of days.

If you cannot obtain them locally, praziquantel and metronidazole can be obtained from the following source online:

In short, I would suggest treating your seahorse tank with a good antiparasitic such as praziquantel or metronidazole, and then concentrate on restoring optimum water quality in your main tank, Sherry. 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.

If this seahorse does not respond to the antiparasitic medications and is unable to recover neutral buoyancy on its own, then you can resort to antibiotic therapy, but I would treat with antiparasitics first of all. I’m not sure if triple sulfa would be helpful for a problem like this, and if you have to resort to antibiotics, I would recommend a medication that includes kanamycin sulfate as its primary ingredient. Kanamycin dissolves well in saltwater, is not adversely affected by the alkaline pH, and is a broad-spectrum antibiotic that is absorbed readily through the skin and gills of the seahorses.

Best of luck resolving this problem.

Pete Giwojna, Ocean Rider Tech Support

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