Gill Disease can be caused by fungal infections, presence of bacteria or parasites, high ammonia or pH levels, low oxygen levels or overcrowding in the aquarium. The unbalanced water damages the gills and provides an opportunity for bacteria to invade the compromised area. All types of fish, marine and freshwater, are susceptible to Gill Disease.


Symptoms of this disease can include hovering at the surface of the water or lying motionless at the bottom, rapid gill movement, swimming aimlessly, swimming slowly, swollen and red gills, and white to gray spots on the gills.


In addition to the above symptoms, Gill Disease can be diagnosed microscopically with gill tissue mounts. Analyzing the water quality and chemistry can also determine if there is a gill irritant present in the water.


A partial water change should be performed. Change 25 to 50 percent of the water and replace with fresh, conditioned water. It may also be necessary to add an anti-bacterial agent to the water.

If both of these treatments fail, you may want to try a chemical solution or medication. Consult with an aquatics specialist for guidance.


If the disease is diagnosed and treated early, there is a chance that most fish will survive.


The best way to prevent Gill Disease is to have clean water, a good filtration system, a good level of aeration and the right amount of fish for your size tank. Avoid overcrowding.