Masculinización de la tilapia del Nilo Oreochromis niloticus (Actinopterygii: Cichlidae) por inmersión en Fluoximesterona y Testostesterona enantato

the effect of the hormone fluoximesterone (f) and testosterone enanthate (t) were evaluated in the growth, survival and the sex ratio of offspring of oreochromis niloticus. in 50 liter tanks, 38 larvae were placed in each experimental unit. treatments were triplicated: f4 400 μg？l-1; f12 1.200 μg？l-1;f20 2.000 μg？l-1; y t4 400 μg？l-1; t12 1.200 μg？l-1; t20 2.000 μg？l-1, as well as controls for water (a) and water plus alcohol (ea). the rate of growth was measured in length (tec-l) and in weight (tec-p). the experiment ended when the fish had reached an age of 138 days after fertilization (dpf). the sex ratio was determined by the direct observation of the gonad using a stereoscope and a compound microscope. after the experiment concluded, there were no significant differences in tec-p, tec-l, nor in survival in the treatments and controls. in the sex ratio, there were significant differences between treatments, indicating that f20 (93%) was significantly higher than controls a (58%) and ae (62%) and treatments f12 (72%), t4 (69% ), t20 (65%). f20 was statistically similar to f4 (79%) and t12 (73%). treatments f4, f12, t4, t12 and t20, showed no significant differences compared to controls a and ae. the masculinization obtained with treatment by fluoxymesterone immersion (2000 μg？1-1) allows us to consider this procedure as efficient for the production of male progeny of tilapia