Resumen

TORRES-HERNANDEZ, Pablo; NUCAMENDI-RODRIGUEZ, Graciela Beatriz; PINTOS-TERAN, Pablo  y  MONTOYA-MARQUEZ, José Alberto. Masculinization of Nile tilapia Oreochromis niloticus (Actinopterygii: Cichlidae) by immersion in fluoximesterone and testosterone enanthate. Zootecnia Trop. [online]. 2010, vol.28, n.3, pp.341-351. ISSN 0798-7269.

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

Palabras clave : sex reversal; inmersion; steroids; fluoximesterone testosterone enanthate.