Diplomonad caused infection in aquarium fish in Serbia

Abstract

Although commensals in digestive tract of a large number of fish species, diplomonads represent very significant opportunistic pathogens. For so far unknown reasons, they can proliferate uncontrollably and thus cause changes in the skin and internal organs in aquarium fish. The problem is confusion over nomenclature of the two most important genera: Spironucleus i Hexamita. Aquarium fish species in which there were diagnosed changes in the skin caused by diplomonads were: Microgeophagus ramirezi, Apistogramma cacatuoides, Apistogramma nijsseni, Symphysodon aequifasciatus, Pterophyllum altum, Archocentrus nigrofasciatus, Pelvicachromis pulcher i Labidochromis caruleus. The fish were treated with 250 mg tablets of metronizadole dissolved in water, or metronizadole in a concentration of 6.6 mg per liter of water. The treatment was successful in only 9 out of 45 treated fish. In the others the symptoms reappeared after certain time. It is necessary to determine the prevalence of the infection in aquarium fish in Serbia, and also examine the success of the treatment with metronizadole applied in food or even other possibilities of the treatment.