Gas Bubble Disease:

What the heck is it?

By Ann Gibler

The first thing that it is important to understand about Gas Bubble Disease (GBD) is that it is not actually a disease itself, but an umbrella term for gas-associated symptoms common to seahorses. A variety of underlying problems, both bacterial and environmental, can present as GBD. There are three areas of the seahorse where the gas-related symptoms collectively referred to as GBD manifest: gas bubbles within the skin (External Gas Bubble Disease), gas buildup within the body (Internal Gas Bubble Disease), and gasses in the pouch (Pouch Emphysema).

External Gas Bubble Disease

External Gas Bubble Disease is the term used for gas bubbles found in the skin. The bubbles in the skin that are associated with EGBD are gas-filled and positively buoyant. They should not be confused with the fluid-filled cysts and granulomata associated with other common seahorse ailments like vibrio and mycobacterial infections.

Gas bubbles can present themselves just beneath the skin anywhere on the seahorse. If large enough or present in great enough numbers, the buoyancy of the gas bubbles can hinder a seahorse’s ability to swim and hitch, and therefore feed properly.

EGBD is likely the result of an error in the hydration of carbon dioxide to carbonic acid by the enzyme carbonic anhydrase, gas super-saturation in their environment, or a bacterial infection in which CO2, released by the bacteria, is trapped in the skin. The manifestation of gas bubbles in the skin has been successfully treated through the use of antibiotics, carbonic anhydrase inhibitors, and changes to the environment including the removal of skimmers. It is important to note that since EGBD is a symptom, each case could have a different cause and therefore require a different set of treatments.

External gas bubble disease can manifest itself anywhere on a seahorse's body. It often appears on angular areas of the body such as spines or between the sides and back.


Often, external gas bubble disease occurs on the tail of afflicted seahorses. Some anecdotal evidence suggests that only male seahorses can be affected on the tail.
Advanced cases of internal gas bubble disease usually damage internal organs to the point of no return. Unfortunately, there is little that can be done at this point.

Internal Gas Bubble Disease

Internal Gas Bubble Disease describes the presence of gas within the body of the seahorse that cause bloating and positive buoyancy. This should not be confused with the bloating of edema, which would cause sinking rather than floating. IGBD presents as the bloating of the seahorse’s body and/or tail, causing the seahorse to be positively buoyant. This often results in the seahorse being unable to direct its movements or descend, and can hinder its ability to feed and to reach the security of hitches under the surface. In advanced cases, IGBD can cause severe damage to the seahorse’s internal organs.

IGBD-like symptoms may be the result of an error in the hydration of carbon dioxide to carbonic acid, gas super-saturation in the environment, or bacterial infection, similar to EGBD. However, the symptoms associated with IGBD could also be manifesting as the result of other non-GBD illnesses like damage or infection of the swim bladder. Like EGBD, antibiotics, carbonic anhydrase inhibitors, and environmental changes have shown to be effective against IGBD, but the treatment required depends on the underlying cause of the condition.


  • severe bloating of the entire body
  • external gas bubbles
  • exophthalmia
  • extreme buoyancy and movement complications

Pouch Emphysema

Pouch Emphysema is characterized by air trapped in the pouch of the male seahorse. This condition, like EGBD and IGBD, can cause the seahorse to float and interfere with his ability to swim, hitch and feed. The suspected causes of PE include micro-bubbles in the aquarium and error in the hydration of carbon dioxide to carbonic acid. The micro-bubbles referred to are not those produced by air stones and water overflow to a sump, but rather the microscopic bubbles like those produced under pressure by some skimmer designs or by air leaks before water pumps.

In most cases, pouch emphysema can be cured with a simple pouch evacuation. >>View article on pouch evacuations

PE can be relieved successfully through manual evacuation of the pouch. Persistent or reoccurring cases of PE have been treated with methods including flushing the pouch with carbonic anhydrase inhibitors and treatment with antibiotics, as well as modification of the environment to prevent micro-bubbles or release them through gas exchange. As always, to prevent reoccurrence, effort needs to be made not only to treat the symptoms, but to identify and correct the underlying source of the problem.


  • grossly bloated/swollen pouch
  • severely hindered locomotion and
  • buoyancy problems

Suggested Further Reading, Websites and References:
Working notes: a guide to seahorse diseases
by Belli, M.D., Driscoll, Lamont et al.

Photo Credit:
dejavu (Louise Tsai), EdHoward (Ed Howard), Feathers&Fins (Karen) and tuwhada (Christina)

Most recent revision: March, 2008

Copyright 2008
All Rights Reserved

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