Prevention of Diseases Start with good water. Clean out decaying matter. Understand and recognize fish diseases. Some bacteria serve a very useful function within your aquarium system. These helpful bacteria attack certain toxicants and diseases in the water.
Furunculosis is a water-borne bacterium, which does exactly that.
It enters the fish through scratches on the skin or through the digestive tract, destroys the fish's defense, breaks down the blood vessels allowing blood and serum to leak out into the surrounding tissues and kills the fish. Fungus Fungus will be a major activity in your aquarium. It can become a serious source of disease-related problems if not kept under control. Your entire tray of eggs can become a solid mass of fungus. If you filled your aquarium with stream or lake water you brought protozoans with it.