Name of disease: Hole-in-the-head Disease.
Other names: Hexamita.
Type of disease: Currently unclear. May be parastical, bacterial, nutritional or environmental
Occurrence: Not common, but affects all types of freshwater fish
Symptoms include: Small holes appear in the fish's body, usually in the head region. These may gradually develop into tubular eruptions with cream-colored or yellow strings of mucus trailing from them. Fish are lethargic, stop eating and may develop a hollow-bellied appearance. Faeces may become pale and stringy. Lesions may also develop at base of fins and along lateral line, and fins and skin may also erode, body may become milky in appearance and slime coat begins to come off in strands.
Unclear. At one time the parasite Hexamita was thought always to be responsible, but in later years nutritional deficiencies, poor lighting, poor water quality and profound stress (e.g. due to overcrowding or lack of oxygen) are thought to be more common causes. Bacterial infection can also be involved.
Treatment: Remove affected fish to hospital tank and keep water quality perfect. Treat with a medicated food such as Medigold (if fish is still eating) or if not with another medication containing Metronidazole (if in UK, obtain Metronidazole from vet, as ordinary anti-bacterial medications will not work on this disease). Salt at a .3% solution may help and will also aid in preventing secondary infections. Feed various highly nutritious foods, such as krill, bloodworms, brine shrimp, Pro-Gold pellets (US) or Hikari pellets (UK).
Precautions: Salt and medications may affect the cycle so monitoring water quality during treatment is essential. Lesions may attract secondary infections such as fungus (continue treatment for Hole-In-The-Head however, rather than stopping and attempting to treat secondary problems). It is also important to find the cause of the problem: check water quality, tank conditions, nutrition (e.g. stale food), lighting, other infected fish..