Sex revesal of Nile tilapia (Oreochromis niloticus) Supreme variety, fingerlings submitted to different temperatures for sexual differentiation phase Invers o sexual de alevinos de tilápias do Nilo (Oreochromis niloticus) variedade Supreme, submetidos a diferentes temperaturas durante fase de diferencia o sexual

This experiment evaluated the effects of temperature on sex inversion survival and presence of deformities in larvae of tilapia subjected to the following treatments control (28oC + diet 60 mg kg-1 of 17 ?-methyltestosterone), 28, 30, 32 and 34oC. The results showed a statistical difference between the proportion of males, with temperatures control, 32 and 34oC (98, 91, 96%, respectively) showed better results than those obtained for treatments 28 and 30oC (71 and 82%). The survival observed in different treatments were 90.74, 90.49, 88.20, 85.43 and 82.16 for the control, 28, 30, 32 and 34oC, respectively, and there was statistical difference between treatments 32 and 34 oC, only when these were compared with the control. In the analysis of the radiographs was not possible to observe the presence of morphological changes in fish subjected to different treatments. With this experiment, we concluded that the temperatures of 32 and 34°C were able to genetically larvae masculinizing females, and that there was no increase in mortality and the presence of deformities could be attributed to treatment. This technique is an alternative to use of steroid hormones. Este experimento avaliou os efeitos da temperatura na invers o sexual, sobrevivência e presen a de deformidades em larvas de tilapia submetidas aos seguintes tratamentos controle (28oC + ra o 60 mg kg-1 de 17 ?-metiltestosterona), 28, 30, 32 e 34oC. Os resultados demonstraram diferen a estatística entre a propor o de machos, sendo que as temperaturas controle, 32 e 34oC (98; 91; 96 %, respectivamente) apresentaram resultados superiores aos obtidos para os tratamentos 28 e 30oC (71 e 82 %). A sobrevivência observada nos diferentes tratamentos foram 90,74; 90,49; 88,20; 85,43 e 82,16 para o controle, 28, 30, 32 e 34oC, respectivamente, sendo que houve diferen a estatística entre os tratamentos 32 e 34oC, somente quando estes foram comparados com o controle. Na análise das radiografias n o foi possível observar presen a de altera es morfológicas nos peixes submetidos aos diferentes tratamentos. Com este experimento, concluiu-se que as temperaturas de 32 e 34oC foram capazes de masculinizar larvas geneticamente fêmeas, e que n o houve incremento na mortalidade e na presen a de deformidades que possam ser atribuídas aos tratamentos. Essa técnica é uma alternativa para a utiliza o de horm nios esteroides.