Most goldfish owners have encountered fish that suddenly become unable to submerge. Try as they might, they float, often belly-up, at the surface, and seem to be in great distress. Less often, the hapless victims may be unable to rise to the surface, or may swim in an “off balanced” or head-down position. Fantails, Orandas and other strains with rounded bodies are the most common victims, but Comets and others are not immune. The problem is also frequently seen in Bettas, or Fighting Fishes, but may afflict any species. Swim Bladder Disease almost always involved. This condition is actually a general term applied to a wide variety of ailments, rather than a specific disease per se. Today we’ll look at its causes, prevention and treatment.
The Swim Bladder
The swim bladder is a sac-like organ located in the abdomen of most bony fishes, but is absent in the cartilaginous fishes (sharks, rays and their relatives). The lining of the swim bladder, and the many blood vessels that transverse it, allow gasses to be passed into and out of the organ. Goldfishes and certain others are also able to exchange gasses through a duct or opening in the bladder that leads to the esophagus. In this manner, fishes control their buoyancy, or ability to float and move up and down in the water column.
Swim Bladder Disease
In general terms, Swim Bladder Disease can be described as a malfunctioning of the swim bladder. Victims typically struggle at the surface but cannot submerge, but others sink to the bottom or swim in an odd manner, as described earlier. A wide variety of causes have been identified.
Causes of Buoyancy and Swimming Problems
Swim Bladder Disease most often arises when pressure is brought to bear on the bladder. The pressure itself may be caused by a variety of conditions, such as over-eating, a blockage in the digestive tract (inability to pass wastes), a tumor, cyst or other growth, retained eggs or young, or a physical injury. Once the bladder in compressed, gasses may be trapped within, unable to enter, or both.
Somewhat related to over-eating is the use of dry fish foods such as flakes and pellets. If these foods are gulped down quickly, before they have absorbed much water, they may swell within the digestive tract and put pressure on the swim bladder. Low water temperatures can exacerbate the problem by slowing digestion.
Bacterial and Viral Infections
During my years working at the Bronx Zoo, aquatic amphibians were sometimes rendered unable to submerge. In nearly all cases, gasses produced by bacterial infections were at the root of the problem. I do not believe this has been documented in fishes, but it may be worth considering. Viral diseases that disrupt diffusion through the bladder’s lining have also been implicated in Swim Bladder Disease.
Orandas and similarly-shaped goldfishes seem prone to Swim Bladder problems due to the configuration of their bodies. Selective breeding for a rounded body has likely changed how the organs are situated, and how close they are to one another (when compared to, for example, a comet goldfish). Pressure builds up quickly when anything is amiss within the body.
Keeping your fishes at the proper temperature and pH (considering the species) and maintaining excellent water quality will strengthen the immune system and enable them to fight off many of the causes of Swim Bladder Disease. Water testing kits are essential for all fish keepers, including those with goldfishes and bettas. Please post below if you need specific information on the needs of the fishes that you keep.
Pre-soaking of pellets and flakes has been suggested as a means of avoiding the swelling issue discussed earlier.
Treating Swim Bladder Disease
Bacterial or viral infections should be treated with appropriate medications. Please post below for further information.
If an impaction is suspected (i.e. if no waste products have been passed), try withholding food for 3-4 days. Depending upon age and species, this will not harm your fishes…some can even handle week-long fasts. Be sure that the temperature is correct for your species, and then slowly raise it a degree or two, while remaining within the safe range, in order to speed digestion.
Lowering the water level may limit struggling and assist those that need to surface for air.
Removal of gasses via aspiration of the swim bladder is possible, but should only be done by a veterinarian or other trained professional. Please see the article linked below for information on a related procedure to remove gasses from seahorse pouches. I’ve worked with zoo and aquarium veterinarians who have operated on the swim bladders of large fishes, but I’m not certain if such is ever done in private practice. Please post below if you would like further information.
Some aquarists recommend the use of skinned frozen peas. The peas are lightly steamed or micro-waved for 20 seconds, and then fed to ailing fish. A 2-3 day fast prior to the feeding may be useful. Rapid cures have been claimed, although details as to the mechanics of the process are not clear.