When To Call The Vet - Common Fish Diseases

Fish are very common pets that people often think of as low maintenance. While some species fit this definition, fish can get sick just like any other pets. As a fish owner, it is important to have knowledge of the most common diseases that could afflict your pet, and how to spot and treat them as well. Some common fish diseases can be treated by owners, while others may require the help and expertise of a qualified veterinarian.


Ick, or White Spot Disease, is a very common and very contagious disease that affects fish. Ick causes fish to develop little, grain-like spots all over their body. In addition to acquiring spots, a fish may also try to rub itself against hard surfaces in the aquarium, almost making it appear as if the fish is trying to scratch an itch. Ick is a parasitic disease where the parasite spends part of its life on the skin of the fish, where cysts develop. These cysts can then fall off the fish, releasing thousands of new parasites that can prey on other fish in the aquarium. If not noticed in the early stages, Ick can be very difficult to control. Adding salt to aquarium water can help but care must be taken as different species of fish tolerate salt levels differently. There are also medications available for treating infected fish.

Fin Rot

Fin rot, as the name suggests, affects fish fins. It can cause them to turn opaque and possibly even become blood streaked. The fin can continue to erode until the rot reaches the base of the fin, at which point the fish will die. Fin rot is caused by bacteria and is not something that normally affects healthy fish. Those that are stressed or have already damaged fins are far more susceptible to fin rot. Over the counter antibacterial medications can be used to treat fin rot.

Swim Bladder Disease

A fish's swim bladder is what helps them to remain buoyant. When there is an issue with the swim bladder, a fish will lose its buoyancy, and this is one of the first indications that it may be suffering from swim bladder disease. Swim bladder disease can develop when the membrane of the swim bladder has been damaged. There is a lot of debate as to what causes swim bladder disease in addition to debate over how to treat it.


Dropsy is a disease that can be caused by bacteria and viruses, and is easily mistaken as a pregnant fish. Dropsy causes a swollen or hollow abdomen, hence the common misconception that the fish is pregnant. Fish suffering from dropsy will lose their appetites and become listless, and once damage from the disease reaches the kidney, it basically becomes incurable. It is thought that infected food, and bad water can lead to dropsy outbreaks in aquariums. Unfortunately, even when dropsy is discovered early, it can be very difficult to cure. There are commercially available remedies that can help with the treatment of dropsy.

Fungal Infections

Fungal infections can be a common issue with fish as fungus spores are almost always present within an aquarium. Fish that have already damaged skin or gills are more susceptible to fungal infections. These infections are typically secondary, and the main symptom is a white growth that looks a bit like cotton on the body of the fish. Anti-fungal medications are available to help treat these infections and many of these medicines also fight bacteria, providing even more protection.

Gill Disease

Gill disease can be caused by fungi, bacteria, and parasites found in water. Fish that suffer from gill disease appear to be hurriedly swimming but do not move at all. They also sometimes appear to be gasping for breath, while flapping their fins very fast. The gills of a fish suffering from gill disease can also become discolored and swollen. Treatment of gill disease involves first improving water quality. Adding an antibacterial solution to the water might also be necessary to cure the fish.

Anchor Worms

Anchor worms are parasites that attach themselves to infected fish. They are also able to burrow into the fish's skin and enter the muscles. Once this happens, the worms develop and release eggs prior to dying. This causes damage to the fish that can lead to infection. Fish that are suffering with anchor worms often look like they have little whitish colored threads protruding from their bodies. One treatment option is to physically remove the parasites from the fish and clean the wounds with antiseptic solution. The other common treatment is bathing the affected fish in saltwater for approximately five minutes for a few days in a row until the parasite falls off.

In addition to the diseases listed above, fish can suffer from many different diseases and infections. When deciding on a species of fish to keep as a pet, owners should do sufficient research and educate themselves on common issues that the particular species suffers from so that any problems can be spotted early on and then dealt with properly.