Ornamental fish are often raised on fish farms where they receive limited treatment for parasitic diseases. Some aquarium fish are also still collected from the wild, where they may have naturally occurring parasites. The fish often arrive to the fish retailer with external parasites and should be treated with appropriate medications to reduce parasites before being sold to customers. Appropriate diagnostic tests need to be conducted to determine which parasites are present; often more than one type can be found on the fish. Each type of parasite needs a different medication to treat it effectively.
The most common protozoal parasites seen on freshwater aquarium fish include the Ciliates : Chilodonella , Epistylis , Ichthyophthirius (Ich), Tetrahymena , Trichodina; Flagellates : Hexamita/Spironucleus , Ichthyobodo (Costia), Trypanosome; Sporozoa : Eimeria , Goussia ; Myxozoa: Dicauda , Henneguya ; Myxobolus ; Microspora : Glugea , Microsporidium , Pleistophora.
Treating the fish involves using medicated dips or by adding medication into the aquarium water. Some medications can also be supplied in the food. Medicated food containing metronidazole can be used for treatment of intestinal protozoal parasite infestations and should be fed for a minimum of 3 consecutive days. Repeated treatments may be necessary to effectively treat some parasites.
External protozoa are best treated using formalin or formalin/malachite green solution. Formalin effectively kills protozoan parasites on gills, skin, and fins. Formalin is not effective against internal infestations. Hydrogen peroxide, copper sulfate and potassium permanganate are also useful in certain species for treating external protozoa. The fish should be checked after treatment to ensure that the parasites have been completely cleared. Retreat as necessary prior to selling fish from the stores.
Key Words: Parasites, protozoa, ornamental fish
External crustacean parasites (anchor worms, fish lice) can be treated by adding diflubenzuron to the tanks of affected fish.
Monogenean trematodes (gill and skin flukes) are treated with fenbendazole. Since fenbendazole powder is not water soluble, it must first be dissolved in a small volume of alcohol, and then added to the water. Digenean trematodes (encysted flukes) live in the intestines, gills, and muscles of the fish, which acts as the intermediate host. Oral fenbendazole can be used to treat the fish for Digenean flukes. Intestinal nematodes (Camallanus, Capillaria) can also be treated by feeding the fish a fenbendazole or mebendazole medicated fish food.
Key Words: Parasites, protozoa, flukes, ornamental fish