Resumen

GUTIERREZ-SIGUEROS, Irma et al. Optimal time and dose of fluoxymesterone, for masculinization of Mayan fish Cichlasoma urophthalmus (Percidae: Cichlidae). Cuadernos de Investigación UNED [online]. 2018, vol.10, n.2, pp.416-421. ISSN 1659-4266.  http://dx.doi.org/10.22458/urj.v10i2.2170.

The production of all-male populations in cichlid fish, is crucial to obtain high yielding in fish farming. The aim of this paper was to determinate the optimal dose and time of exposure to fluoxymesterone (FM), during the masculinization of Mayan cichlid Cichlasoma urophthalmus larvae. Therefore, two periods of exposure to FM (45 and 60 days) and four androgen doses (0, 15, 30 and 60mg/kg of food) were tested, having a total of five treatments with FM (15mg 60d, 30mg 45d, 30mg 60d, 60mg 45d and 60mg 60d) and one control group (0mg 60d, CTL), in triplicate. One kilogram of Purina tilapia starter feed (45% protein) was sprayed with a hormone solution previously dissolved in ethyl alcohol, according to each separate testing dose mentioned above. C. urophthalmus larvae were fed hormonal foods ad libitum (seven days after hatching) based on each treatment. Results revealed that male average rate (69,1±2,7%) obtained from the 60mg/kg of FM dose, administered with food for 45 days (60mg 45d) was significantly greater in comparison to the other tested treatments (Tukey, p<0,05, k = 6, N-k = 12). Thus, it is necessary to review new techniques to administer steroid hormones (bioencapsulation) that, on one hand, reduce precocious reproduction problems in the cultivation of this species and, on the other hand, establish more environmentally friendly techniques, which could minimize the presence of steroid hormone waste on aquatic ecosystems.

Palabras clave : Time; dose; fluoxymesterone; masculinization; Cichlasoma; urophthalmus.

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