Ornamental Fish Production and Management

10.1.3 Protozoan diseases

(i)Velvet or Rust

Symptoms: Clamped fins, respiratory distress (breathing hard), yellow to light brown "dust" on body.

This disease has the appearance of a golden or brownish dust over the fins and body. The fish may show signs of irritation. The gills are usually the first thing affected. Danios seem to be the most susceptible, but often show no discomfort. This disease is highly contagious and fatal. The best treatment is with copper at 0.2 mg per liter (0.2 ppm) to be repeated once in a few days if necessary. Acriflavine may be used instead at 0.2% solution (1 ml per liter). As acriflavine can possibly sterilize fish and copper can lead to poisoning, the water should be gradually changed after a cure has been effected.

(ii)Costiasis

Symptoms: Milky cloudiness on skin.

Similar treatment followed for velvet diseases may be done.

(iii)Ich (Ichthyphthiriosis)

Symptoms: Salt-like specks on the body/fins. Excessive slime. Problems breathing (ich invades the gills), clamped fins, loss of appetite. The drug of choice is quinine hydrochloride at 30 mg per liter (1 in 30,000). Quinine sulphate can be used if the hydrochloride is not available. The water may cloud but this will disappear. By reducing the time (with raised temperature) of the phases, you should be able to attack the free swimming phase effectively.Most commercial remedies contain malachite green and/or copper, which are both effective.