The condition commonly known as gas bubble syndrome (GBS) is probably the most common health problem for home aquarists keeping seahorses. Gas bubble syndrome is believed to be caused by gas pockets forming within the tissue of the brood pouch of males, the eye or the muscular prehensile tail. When GBS occurs in the brood pouch of the males the condition is called chronic pouch emphysema and results in positive buoyancy. Chronic pouch emphysema is by far the most common form of GBS and is restricted to males, as females do not have a brood pouch. When GBS occurs in the capillary network behind the eye the condition is known as Exophthalmos. In this case, the affected eye or eyes can become enormously swollen. When it affects the capillary network of the gas bladder, hyperinflation of the swim-bladder occurs and again results in positive buoyancy.
What is Gas Bubble Syndrome?
First of all, it is important to understand that GBS is not actually caused by air getting into the pouch. Rather, the gas is formed inside the pouch (marsupium) itself. The pouch will usually continue to expand with gas until the seahorse is having problems with positive buoyancy (i.e. the seahorse floats). Secondly, it is important to understand that GBS is NOT a disease, rather it is an environmental problem. Therefore, GBS isn’t contagious and cannot spread from one seahorse to another. As the condition affects the male brood pouch, females are rarely affected. Mature males that are actively courting and breeding are especially vulnerable to chronic pouch emphysema.
How can GBS be treated?
Most forms of GBS are easily treated and cured simply by manually evacuating the gas that builds up within the male’s pouch and then performing a pouch flush and administering acetazolamide. Your access to this drug will be largely dependent on location. There are many guides online on how to evacuate the gas from a seahorse pouch, so I will not go into that here.
While “burping” the pouch to release the trapped gas will provide the seahorse with immediately relief, most of the time this is only temporary as more gas will begin accumulating within the pouch and the problem will reoccur. Burping the pouch does not address the underlying problem that is causing the gas to build up to begin with. Furthermore, repeatedly burping the pouch is not a long-term solution and will eventually result in serious pouch infections that often prove fatal.
As GBS is an environmental problem rather than a pathogenic problem, the best way for the home hobbyist to prevent GBS is to maintain optimum water quality at all times by reducing the organic loading in the aquarium, making sure the tank has excellent surface agitation and aeration to promote efficient gas exchange at the air/water interface and to keeping the substrate of the aquarium clean and sanitary.
Improving the surface agitation and aeration to facilitate better gas exchange between the air and water surface helps to eliminate any potential problems with low-level gas super-saturation of the aquarium water, which is one of the environmental triggers that causes problems with GBS. It will also help to stabilize the aquarium pH by keeping the levels of dissolved oxygen high and the levels of dissolved carbon dioxide low (carbon dioxide lowers the pH of water), which will be very beneficial in the long run. Likewise, anything you can do to provide your seahorses with a stress-free environment will be helpful in preventing such problems in the future.
Main Causes of GBS
1) Insufficient depth:
Seahorses kept in aquaria that are less than 50 cm deep (20 inches) are very susceptible to GBS. The taller the aquarium is the more resistant the seahorses will be to GBS. Taller aquariums have greater hydrostatic pressure, which can prevent the formation of gas pockets. In fact, most forms of GBS can be resolved by immersing the affected seahorse at a depth great enough to cause the gas bubbles to dissolve back into solution.
2) Gas super-saturation:
Gas super-saturation of the aquarium water can directly result in the formation of gas pockets within the blood and tissues of seahorses. Increasing the surface agitation and aeration in the aquarium to promote more efficient gas exchange will help to eliminate potential problems with gas super-saturation.
3) Changes in the seahorse’s blood chemistry (i.e., acidosis):
Anything that tends to acidify the blood of seahorses can result in GBS, including; stress, low levels of dissolved oxygen and/or high levels of CO2 and low pH of the aquarium water.
Therefore, as with all diseases and conditions it is always better to take preventative measures rather than reactionary measures. A well designed maintenance schedule will ensure that your seahorses remain happy and healthy for year to come.