Parasitismo por Philostomella cigarra Szidat e Schubart, 1960 (Isopoda : Cymothoidae) em tilápia-do-Nilo (Oreochromis niloticus)

Abstract

The fish parasitism in intensive culture systems have been commonly verified and associated with high economic losses to aquaculture production. The main pathogens associated with cultured fish are protozoa and monogenetics. The isopods of the family CYMOTHOIDAE can infect a great variety of freshwater and marine fish, with great commercial interest, shifting the host physiology. In the river basin of rio Grande Lavras-MG, Galeocarax knerii (“saicanga” or “bitch-fish”) is the isopod natural host, however, the parasitism of other fish species like Oreochromis niloticus and Salminus maxillosus have been observed. The aim of this work was to evaluate the effect of isopoda infection in Nile tilapia in experimental conditions. The isopod was previously identified as a CYMOTHOIDAE of the Philostomella cigarra specie. The parasite showed high specificity to the natural host Galeocharax knerii, being the buccal cavity the main site of infection. The parasitism of Nile tilapia in experimental conditions was transitory. Adult parasite caused ulcerative lesions and high mortality. Unusual swimming, excitation, misfeed, hematological alteration and tongue histological microscopic lesions were observed in tilapia infected with young parasite.