Goldfish can contract a variety of diseases, especially parasitic and fungal illnesses. But they are far less likely to get disease in the first place if pet owners provide healthy water conditions and are careful not to introduce infected fish into the tank. Although untreated or severe cases may kill fish, many goldfish diseases have cures.
Ich, which is short for ichthyophthirius multifiliis, infects fish and gives them white spots. This parasite attaches itself to the gills and skin of the goldfish and damages its tissue. The fish may become lethargic and hang out on the bottom of the tank, according to Purdue University. To cure ich, fish owners can put commercially available chemicals in the fish tank water. According to the University of Florida, fish owners should treat the disease as soon as possible, because fish with very severe ich outbreaks may die during treatment.
The chilodonella parasite infects freshwater fish, including goldfish. According to the University of Florida, fish with chilodonella problems secrete excessive mucus and act irritated. The disease organism is visible under a microscope, and can be treated easily with commercially available chemicals. Without treatment, the fish can die.
Branchiomycosis is a fungal disease also known as "gill rot". Both wild and pet fish, including goldfish, can get this disease. The fish gill tissue starts dying and infected fish tend to gulp for air at the surface of the water. The best way to cure this disease is to provide ideal tank conditions for the fish, since branchiomycosis usually only starts out in poor tank conditions, according to the University of Florida. After an infection occurs, formalin and copper sulphate can help treat it, although the entire tank and its contents should also be sanitised.
Saprolegniasis affects both fish and fish eggs. This fungus grows on eggs and injured parts of fish, according to the University of Florida. The fungus looks cotton-like and appears on the fish or its eggs. It is best to prevent the fungus from starting in the first place rather than to treat an existing infection. The fungus occurs less frequently in tanks with good circulation and clean water. Fish owners can also prevent it by keeping goldfish away from other aggressive fish that might wound them. Once an infection takes over, fish owners can treat it with a variety of commercially available chemicals, including formalin and povidone iodine solutions.