Sex revesal of Nile tilapia (Oreochromis niloticus) Supreme variety, fingerlings submitted to different temperatures for sexual differentiation phase

Abstract

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.