In a pond setting, infected fish may congregate in shallow water. The parasites behind this disease may lie dormant in a membrane at the bottom of some aquariums waiting to strike weak fish. Treatment Chemical treatment is usually aimed at combating the disease in its dormant phase at the bottom of the tank. The white spot parasite is immune to treatment when attached to the outermost layer of the host's skin. Gradually, infected white regions spread more densely around the mouth, and red ulcers appear on other parts of the body.
Fins also become frayed.
In advanced cases, the disease spreads to a fish's internal organs. Infected fish often refuse to eat and become thin. Imported freshwater fish often bring cotton wool disease, but abrupt changes in water conditions, overstocking and not changing tank water can also promote it. An aquarium antibacterial can be effective if the disease is caught before it spreads to internal organs. Once the disease spreads to the internal organs, individual antibiotic treatment is necessary.