Ichthyophthirius multifiliis Fouquet, 1876 is a ciliate parasite causing white spot disease and may cause high mortality in fresh water fish species. Telescope fish (Carrassius auratus) 1.97 (+/- 0.51) g in weight were experimentally infected with 1. multifiliis at 23 (degrees) under barC water temperature. After that 2 different dosages (24 and 36 mg/kg body weight) metronidazole, secnidazole and ornidazole were added to feed and administered to fish for 10 days. One day later, skin scrapes were taken from fish and the slides were investigated under the microscope. At the end of the experiment, no parasite was found in groups which received 24 mg/kg metronidazole and ornidazole. All three of the chemotherapeutants were also efficacious at 36 mg/kg dosages for treatment of the disease.