That Fish Blog – Aquarium Advice and Information

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. Read More »