Dear Martin:

Pete Giwojna

Dear Martin:

I’m very sorry to hear about the problems that your stallion has developed, and I would be happy to discuss a few of the things that might be helpful if you feel it is worth the effort.

However, I must advise you that internal gas bubble syndrome (GBS) is much more intractable and difficult to resolve then the subcutaneous emphysema or external GBS you have dealt with in the past, sir, for reasons we will discuss in more detail later in this post. The prognosis is generally very poor when dealing with internal GBS as a home aquarist, and it may well be that none of the measures I will describe for you will be able to reverse this problem and produce a good outcome at this point…

As you know, gas bubble disease is not at all contagious; it isn’t caused by any sort of pathogen, so you needn’t be concerned that it is going to spread to the rest of your herd like an infectious disease, Martin. Since it is not actually a disease process, I prefer to refer to gas bubble disease as a syndrome and call it gas bubble syndrome (GBS). Even though it is not an infectious disease, the rest of your seahorses are still not in the clear, Martin.

Be aware that GBS is an environmental disease which is triggered by certain conditions within the seahorse tank itself, so you will need to correct the conditions in your aquarium or the rest of the seahorses could also be at risk. (Because of their heavily vascularized, physiologically dynamic brood pouch, mature males that are actively courting or breeding are the most susceptible to GBS.)

One of the measures that sometimes helps with internal GBS is to pressurize the seahorse at depth in a tall container, Martin. As a rule, the deeper the container and the greater the hydrostatic pressure at the bottom, the more effective recompressing and then decompressing the seahorse will be in relieving this type of problem.

You can also consider partially deflating the seahorse’s swimbladder by performing a needle aspiration in order to help relieve the positive buoyancy, and treating the seahorse with acetazolamide (brand name Diamox) and/or antibiotics at the same time as you are pressurizing him in the deep container. I will explain all these options in more detail for you below:

As you know, the swelling in the chest and abdomen of your seahorse is due to a different form of gas bubble syndrome. When the gas emboli that trigger GBS form in the capillary network of the gas bladder (the rete mirabile), hyperinflation of the swimbladder occurs, resulting in positive buoyancy. And when intravascular emboli occur deep within the tissue and occlude blood flow, generalized edema results in the affected area. Or extravascular emboli may cause gas to build up within the coelom, often resulting in positive buoyancy and swelling or bloating of the abdominal cavity (internal GBS).

That’s what’s happening to your stallion, Martin. New gas emboli have formed and are either causing the gas bladder of the seahorse to become overinflated, or are causing gas to build up within the coelomic cavity of your male, or both. This condition is known as internal GBS, and it is much more difficult to resolve successfully then external GBS (i.e., subcutaneous emphysema or bubbles).

There are a few treatment options in such cases:

(1) First of all, you can try manually deflating your stallion’s gas bladder. If the bloated chest and abdomen he has developed is due to a hyperinflated swimbladder, releasing some of the excess gas and partially deflating the gas bladder may provide him with relief and counteract the tendency to float.

(2) Secondly, you can try pressurizing him at a depth of at least 40 inches in a homemade decompression chamber.

(3) Thirdly, you can try treating him with the Diamox or Diamox plus antibiotics while he is being pressurized in the deep container or in a hospital tank.

The simplest of these is to manually deflate is swim bladder using a fine-gauge hypodermic needle and syringe, which is a procedure we’ll discuss in more detail below.

Manually deflating the swimbladder is accomplished much like a needle aspiration, except the needle is inserted into the gas bladder rather than the pouch. This is how Dr. Marty Greenwell from the shed aquarium describes this procedure in the 2005 Seahorse Husbandry Manual:

“If a hyperinflated swimbladder is suspected, a bright light can be directed from behind the animal to visualize the location and borders of the distended organ. This is useful when attempting to deflate the bladder. The needle should be directed between the scute/plate margins for ease of penetration through the skin. The external area can be rinsed with sterile saline or a drop of triple antibiotic up all my appointments can be applied prior to penetration.”

The seahorse’s swimbladder is a large, single-chambered sac that begins in the band of its neck and extends 1/3 of the length of its body cavity along the dorsal surface. It’s a large organ so if you can visualize it clearly using a bright light (just like candling an egg), releasing some of the gas to partially deflate the swimbladder is fairly straightforward and uncomplicated.

If the problem is a hyperinflated swimbladder, this simple procedure will provide your seahorse with immediate relief and help to resolve the problem. But if you cannot make out the swimbladder clearly or if the problem is due to excess gas building up within the abdominal cavity, rather than a hyperinflated gas bladder, then pressurizing the seahorse a homemade decompression chamber is often your only recourse, as I will discuss with you in more detail below.

In my opinion, Internal GBS is often best treated by recompression-decompression, which can cause the emboli or gas bubbles to go back into solution and be resorbed if you can achieve sufficient pressurization, so that’s also something you should strongly consider, Martin. In your case, I would suggest pressurizing the affected seahorse in a homemade decompression at a depth of at least 40 inches as described below. If you think it would be helpful, he can be treated with antibiotics and Diamox while he is undergoing the decompression cure to help him recover from any infection that may be involved. External GBS typically responds extremely well to treatment with Diamox, but internal GBS is a much more serious condition, and often responds better to pressurization, in my opinion. But if you can combine the pressurization with antibiotic therapy and Diamox, that will increase the chances of a good outcome.

Internal Gas Bubble Syndrome (GBS) is the most dangerous form of this affliction because any of the internal organs in the abdomen can be affected by the gas emboli that form in the seahorse’s blood and tissue, and by the swelling and buildup of pressure within the coelom, yet there are no outward indications of trouble at first, making it difficult to detect the problem until the condition is well advanced and serious damage has been done. The gas emboli occlude vessels and capillaries, thus restricting the blood flow to the affected area, which is what makes the internal form of GBS so insidious — irreversible damage can be done to vital organs or organ systems before sufficient excess gas builds up within the coelomic cavity to cause positive buoyancy and alert their keeper to the problem.

Carbonic anhydrase inhibitors such as acetazolamide (brand name Diamox), which work so wonderfully well when treating external GBD (subcutaneous emphysema), are not as effective in reversing this type of damage, but can be helpful if combined with antibiotic therapy and pressurization.

When treating internal GBS, the outcome often depends on which internal organs were involved and how soon the problem is detected. In my experience, the prognosis and chances for a successful outcome are much better when treatment is begun while the seahorse is still eating. Unfortunately, that can be difficult to accomplish when you’re dealing with Internal GBS because the seahorse remains largely asymptomatic until it becomes bloated and begins to float.

In my opinion, Internal GBS is often best treated by recompression-decompression, which causes the emboli or gas bubbles to go back into solution and be resorbed. It works especially well when hyperinflation of the swim bladder is part of the gas bubble syndrome, since the increase in hydrostatic pressure triggers the capillary-rich oval of the swimbladder to begin resorbing excess gas. Equally importantly, the recompression-decompression cure is a viable option for treating Gas Bubble Syndrome (GBD) for hobbyists who are having trouble obtaining Diamox for one reason or another or for seahorses that are suffering from internal GBS. Anyone can set up a simple homemade decompression chamber and begin treating their seahorse as soon as they can mix up a new batch of saltwater. If you want to give it a try, here is how to proceed, Martin:

The Recompression Cure for Gas Bubble Syndrome

Recompression simply involves placing the affected seahorses in a flow-through cage or enclosure and immersing them for a period of days at a depth with sufficient water pressure to cause the emboli to dissolve. The increased hydrostatic pressure causes the gas bubbles that have formed within the tissue and blood of the seahorse to go back into solution where they can be resorbed, relieving the problem. (This is why a decompression chamber is used to treat divers for the “bends,” caused by nitrogen gas embolisms within the diver’s tissue and blood.) Afterwards, the seahorses are slowly raised back to normal depth/pressure over a period of hours, allowing the total partial pressures of the dissolved gases in the water and the seahorses’ bloodstream to equalize on the way up.

At present, there is no consensus among the professional aquarists who use this method regarding the exact depth and length of immersion needed to effect a cure. I’ve encountered decompression times ranging from 2 days to 10 days and depths ranging from 10 feet in large aquaria (Paul Groves, pers. com.) to over 35 feet at the bottom of the ocean (Bill Stockly, pers. com.), all of which worked equally well. Interestingly, the shortest immersion time was used successfully at one of the shallowest depths (4 meters) and cured seahorses afflicted with all the different forms of GBS (Paul Groves, pers. com.).

While the exact treatment protocol that will produce the best results remains to be determined, everyone whom has tried the decompression cure agrees as to its remarkable effectiveness. It cures external GBS (subcutaneous emphysema, a.k.a. tail bubbles), chronic pouch emphysema (pouch bloat) and internal GBS equally well. In fact, as long as treatment is begun early enough, before the emboli have caused irreversible damage, decompression has a very high cure rate. It is safe, provides the affected seahorses with immediate relief, and seems to work for all forms of GBS.

Of course, the home hobbyist lacks the resources to apply decompression at the sort of depths employed by the professionals. But I am discussing the recompression-decompression cure in some detail for two reasons. First of all, a number of hobbyists have managed to construct homemade decompression tanks and chambers, and other enterprising hobbyists may wish to follow their lead (Lisa Hovis, pers. com.). Homemade decompression devices range from simple tubes of water 6-12 inches in diameter and 4-12 feet tall capped at one end, designed merely to increase hydrostatic pressure, to pressurized wide-mouth bottles complete with pressure gauges and bleeder valves (Lisa Hovis, pers. com.). Secondly, I suspect that when enough data comes in we will find that a depth considerably less than 10 feet and relatively short immersion times will prove to be adequate to resolve most cases of GBS.

For example, while working with the Hawaiian seahorse (Hippocampus fisheri) at the Waikiki Aquarium, Karen Brittain found that all the specimens kept in smaller, shallower aquaria developed subcutaneous gas bubbles within a matter of months, whereas H. fisheri that were maintained in tanks at least 1 meter deep fared much better (Bull and Mitchell, 2002, p37). The Hawaiian seahorse remains pelagic all its life, typically being found at least a mile offshore in deep water, and Brittain speculates that H. fisheri needs to migrate to depths unachievable under normal aquarium conditions to maintain proper physiological balance (Bull and Mitchell, 2002, p37). I think she is absolutely correct. It seems likely that H. fisheri follows a daily vertical migration pattern, perhaps synchronized with the movements of plankton. Her findings suggest that tanks a minimum of 3 feet deep can provide a measure of protection against GBS, and custom-built aquaria of those dimensions are certainly within the realm of the home hobbyist.

This remains a fertile field for future research. It has been suggested that should there be an outbreak of GBS in one of your aquariums, transferring the seahorses to an aquarium at least 3 times as deep as their present tank can decompress the patients and prevent a recurrence of such problems (Wooten and Waughman, 2004). This suggestion has a lot of merit. Even upgrading to a tank that’s twice as deep would be quite advantageous in terms of GBS prevention. Much work remains to be done to develop decompression guidelines for seahorses and to determine what sort of depth is needed to confer protection from GBS to different species. But when it comes to GBS, two things are certain: deeper tanks are healthier for seahorses and recompression can sometimes achieve remarkable recoveries.

In short, many times your best bet to cure internal GBS may be to try a moderate form of recompression to help your seahorse recover. What I have in mind is confining the affected seahorse in a flow-through enclosure at the bottom of a 50-gallon Rubbermaid enclosure 40 inches deep, or something similar, for a period of about 3 days. Once the seahorse is immersed at the bottom of this homemade “decompression chamber,” you cannot raise it to the surface again for daily feedings. Since your decompression chamber will have no biofiltration, I would simply fast your seahorse while it recompresses at depth. It can easily go without eating for a few days and that will help eliminate any ammonia spikes in the meantime.

If you decide to try this, be sure to keep your makeshift decompression chamber well-aerated. A shallow airstone anchored just below the surface — NOT at the bottom of the decompression chamber! — to provide surface agitation and oxygenation should suffice. (CAUTION: submerging an airstone or bubbler more than 30 inches beneath the surface can result in low-level gas supersaturation, which will worsen problems with GBS.)

When the recompression period is finished, raise the seahorse to the surface (or lower the water level in the hydrostatic chamber) gradually, in a series of stages, over a period of several hours, to assure that the patient decompresses completely and the gas emboli don’t reform.

Lighting your homemade decompression chamber isn’t really necessary. Seahorses have outstanding visual acuity and see very well under low light conditions (a couple of species are even said to have adopted nocturnal behavior in the face of heavy fishing pressure), so your stallion will be able to see well under the ambient light levels that penetrate and 50-gallon bucket. You won’t be feeding the seahorse during the period when it’s undergoing the decompression cure, so he doesn’t need to be able to see well enough to hunt small prey or anything like that, and the darkened conditions may give her a sense of security and help her relax, since he won’t be feeling so exposed and vulnerable.

If you want to keep an eye on him periodically while he’s undergoing pressurization, you can just take a quick peek now and then using a flashlight.

When the recompression period is finished, raise the seahorse to the surface (or lower the water level in the hydrostatic chamber) gradually, in a series of stages, over a period of several hours, to assure that he decompresses completely and the gas emboli don’t reform.

One of our other Club members has used this method to cure her seahorse of internal GBS after Diamox baths had been tried unsuccessfully. Here is how Chris described her experience with GBS, and her treatment method with her homemade decompression chamber, in posts to the group:

Hi — After 3 days of diamox Heidi was still buoyant (the diamox did not
seem to have helped at all), and swimming with the tip of her head
sticking out of the top of the water, clearly frustrated with her
situation. I looked at her with a magnifying class, and can’t see any
external signs of bubbles. I also don’t see any signs of bloating or
eye problems.

I followed Pete’s suggestions, took her off the diamox to restore her
appetite, gave her 1 day of rest in the hospital tank with clean water
and Kanamycin. She ate well yesterday and this morning. I rigged up
an inexpensive way of submersing her to 3 times the depth of my 30
gallon display tank. (I priced building a 6 ft deep tank out of an
acrylic tube attached to a base, or acrylic rectangles
attached to a base, and it came out to be anywhere from $250 to $400.
They wanted to charge $175 per linear foot of the acrylic tube thick
enough to safely support a 5 or 6 ft column of water). I’m going to
try the cheap method first, and will build a deeper aquarium if she
needs a greater water pressure.

So-I have her in a ‘critter keeper’ (small plastic container with a
lid that has slots in it and a viewing window in the center) with 2
soft rubber hitching posts. The lid has 4 large criss-crossed rubber
bands on it just in case the lid comes off. I made sure there weren’t
any bubbles underneath the critter keeper or underneath the little
clear viewing lid on the top. I bought a 50 gallon rubbermaid bucket
which gives a water depth of 3 1/2 ft when filled. The critter keeper
is inside a 5 gallon white bucket weighted down with a signature
coral, with a rope tied to the bucket handle (made it easy to lower
into the big bucket). I lowered her slowly this morning, and she
seems fine (not pinned against the lid of the critter keeper, and she
is able to go between the 2 hitching posts). I have an airstone going
at the surface of the deep bucket, as Pete suggested. I can see her
with a flashlight. Her breathing looks normal.

I filled the 50 gallon bucket yesterday with the shower! and let it
‘degas’ for one day (also to make sure that it didn’t spring a leak.
It is in the bathtub). The water temp is 70 degrees. I matched the
specific gravity and ph of the hospital tank.

Heidi is going to remain there for 2-3 days, as per Pete’s suggestion.
After that, I will bring her up very slowly (or unload the water from
the big bucket very slowly). I hope this works! Our big bathroom has
been completely taken over with buckets, hospital tank, salt mix, etc.
Wish us luck!

And here is Martin’s follow-up message after the recompression-decompression treatment was completed:

Hi Pete and Everybody, Heidi is okay! No more floating. I unloaded
the water from my makeshift compression chamber very slowly, as per
Pete’s suggestion, rather than pulled up the critter keeper from the
bottom (much safer to unload the water). I then transferred the
critter keeper she was in to a 5 gal bucket of clean saltwater,
and she swam out when I opened the lid. I decided to do a water
change in the main tank before putting her back in, and used the water
I pulled out of the main tank (74 degrees) to warm up the water she
had been in (70 degrees) to help re-acclimate her to the main tank.
She is eating and swimming as normal, back to her aggressive self with
the turkey baster and Mysis. She is very happy to be back in the
display tank, and is enjoying swimming all around, once again
neutrally buoyant. She was sooo happy to see her favorite coral
colored fake coral. Her color is going back from being dark brown
(her under stress color) to light brown/gold today. I hope to see
her go back to her coral color soon. Thanks for your help Pete!

I hope I never again have a SH with the floaties!
For the record, she was in a critter keeper inside a 5 gal bucket
weighted down with a fake (Signature) coral at the bottom of 40 inches
of water in a Rubbermaid 50 gallon bucket (on wheels-a new bucket). I
had an airstone at the top as per Pete’s instructions. She was in for
2 1/2 days.

For best results, the decompression sure is often combined with antibiotic therapy and treatment with Diamox. It is a simple matter to administer a regimen of antibiotics while the seahorse is submerged at the bottom of the 50-gallon Rubbermaid bucket. (Just don’t perform any water changes while the seahorse is undergoing recompression-decompression.) This would help prevent any secondary infections which are often associated with GBS or stress, and would also cover all the bases if you suspect the underlying cause of your seahorse’s positive buoyancy may be due to a bacterial infection.

For the antibiotic therapy, kanamycin, neomycin, and nifurpirinol are the antibiotics I prefer. I would recommend using two of them (i.e., kanamycin/neomycin or nifurpinol/neomycin) in combination for even greater efficacy, as described below, but if you can only obtain one of them, kanamyacin is the best choice in my opinion:

Kanamycin sulfate

This is a potent broad-spectrum, gram+/gram- aminoglycoside antibiotic. It is wonderfully effective for aquarium use because it is one of the few antibiotics that dissolves well in saltwater and that is readily absorbed through the skin of the fish. That makes it the treatment of choice for treating many bacterial infections in seahorses. Kanamycin can be combined safely with neomycin to further increase its efficacy. Like other gram-negative antibiotics, it will destroy your biofiltration and should be used in a hospital tank only.

nifurpirinol (Furanase)

Nifurpirinol is a nitrofuran antibiotic that is the active ingredient in many commercial preparations designed for use in the aquarium. It is stable in saltwater and rapidly absorbed by fish, making it the preferred treatment for fungal infections in seahorses (Burns, 2002). Nifurpirinol is photosensitive and may be inactivated in bright light, so use this medication only in a darkened hospital tank.

Nifurpirinol may be combined with neomycin (see below) to produce a potent broad-spectrum medication that’s effective against both fungus and bacteria. Nifurpirinol/neomycin is therefore a great combination to use when you’re not certain whether the infection you are treating is fungal or bacterial in nature.

Neomycin sulfate

Neomycin is a very potent gram-negative aminoglycoside antibiotic. Most of infections that plague marine fish are gram-negative, so neomycin sulfate can be a wonder drug for seahorses (Burns, 2002). As mentioned above, it can even be combined with other medications such as kanamycin or nifurpirinol for increased efficacy. For example, kanamycin/neomycin is tremendous for treating bacterial infections, while nifurpirinol/neomycin makes a combination that packs a heckuva wallop for treating mixed bacterial/fungal infections or problems of unknown nature. Keep it on hand at all times.

Neomycin will destroy beneficial bacteria and disrupt your biological filtration, so be sure to administer the drug in a hospital tank.

One other thing to keep in mind is water temperature. Since you’re homemade decompression chamber is unheated, the water temperature will gradually fall over the three-day treatment period. This is fine and to be is expected — and even beneficial in many respects — but it does mean that once the decompression period is over, you may have to acclimate the seahorse for temperature before returning the patient to the main tank.

Okay, Martin, those are my thoughts on the matter. You might consider performing a needle aspiration to partially deflate the seahorse’s swimbladder to relieve the internal pressure and help resolve the buoyancy issues.

Likewise, you might try pressurizing the seahorse at depth using a homemade decompression chamber, as we have discussed above. If you can administer antibiotics and another dose of Diamox while the seahorses being pressurized at depth, that’s even more helpful.

But if the external GBS has already caused irreversible damage or has been ongoing for an extended period, then none of these measures may be able to resolve this problem, so please take that into consideration as well.

Good luck.

Pete Giwojna, Ocean Rider Tech Support

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