White bumps on your aquarium fish can mean a number of different things. Your fish may have contracted a bacterial infection, it may have a parasite problem or could potentially have a fungal infection. White bumps need to be diagnosed properly so treatment can begin and prevent the spread of the disease.
White bumps with red edges are caused by the bacteria known as Columnaris. This bacterial infection is easily treatable with antibiotic therapy, generally a sulfa drug with trimethoprim.
The presence of white bumps can also indicate tumors, both cancerous and noncancerous, that cannot be treated in fish.
Viral infections, such as fish pox, can also manifest as white bumps on fish. These are usually not treatable.
Potassium permanganate is also used to treat various causes of white bumps on fish. Potassium permanganate is a strong oxidizer that can be added to the water in a series of treatments that neutralize bacterial and fungal elements.
Ulcers can appear to be white bumps if they have ruptured and are weeping white pus. These can also be treated with the use of antibiotics or potassium permanganate. These usually occur when the water temperature drops and the fish spend more time along the bottom.