Identification of pathogens in fish polyculture systems in southern Minas Gerais, Brazil

Abstract

Fish diseases represent a significant limiting factor in aquaculture systems. Among the many pathogens, bacteria are probably the most significant group of etiological agents. Thus, the objective of this work was to isolate and to report the incidence of streptococcosis and other possible pathogens in fish polyculture systems in the region of Lavras, state of Minas Gerais, Brazil. Fish samples were randomly collected from seven fish polyculture systems in the region, including the following municipalities: Lavras, Itutinga, Itumirim, Nepomuceno, Carrancas, São Sebastião da Vitória, and Ingaí. The specimens analyzed were: Tilapia (Oreochromis niloticus), Dourado (Salminus brasiliensis), Cará (Geophagus brasiliensis), Curimba (Prochilodus lineatus), Surubim (Pseudoplatystoma corruscans), and Piracanjuba (Brycon orbignyanus). Samples of kidney, brain, liver, spleen, and intestinal tract, and skin scraping was collected and sown in a culture medium. After the incubation period, the microorganisms were identified according to the culture, morphology, dyeing, and biochemical characteristics of the bacteria. Colonies of Streptococci, Aeromonas, and Edwardsiella were identified in Tilapia, Cara, Curimba, and Surubim fish species. The results showed the identification of the bacteria in fish polyculture systems in the region of Lavras, southern Minas Gerais. Therefore, greater sanitary control and the development of other studies to treat diseases related to these pathogens are necessary.