The effects of different proportions of the 17-estradiol and 17-methyltestosterone on growth, sex reversal and skin colouration of the electric blue hap (Sciaenochromis ahli Trewavas, 1935)

摘要

This study was performed to investigate the effects of 17-estradiol (ES) and 17-methyltestosterone (MT) on growth, development, survival, sex ratio and colour change in the electric blue hap (Sciaenochromis ahli Trewavas, 1935). The hormones were not supplemented to the control feed, while six other feeds were prepared by adding 20, 40 and 60mgkg(-1) 17-ES or 20, 40 and 60mgkg(-1) 17-MT to each, resulting in seven different feed treatments. Average live weight of the fish supplemented with these diets was 0.42 +/- 0.04g. At the end of the study, the highest weight gain was observed in fish fed 60mgkg(-1) 17-MT group (2.62 +/- 0.11g) and the difference with the groups fed with 17-ES was found to be significant. All fish fed 17-MT were male, while the rates of feminization in fish fed 17-ES at 20, 40, 60mgkg(-1) were 91.11%, 88.88% and 93.33% respectively. Survival rates were respectively determined as 80%, 95.56%, 84.44%, 93.33%, 77.78%, 84.44% and 84.44% for the control, 20, 40, 60mgkg(-1) 17-ES and 20, 40, 60mgkg(-1) 17-MT treatments. The best colouration was achieved in the 17-MT groups (P0.05). The L* values varied between 32.98 +/- 4.44 and 61.35 +/- 2.19, a* values between -7.06 +/- 0.22 and -3.42 +/- 0.11, and b* values between -7.74 +/- 0.10 and 11.65 +/- 0.03, while Chroma (C*) and Hue (H degrees(ab)) angle values varied between 7.54 +/- 0.22 and 13.60 +/- 0.01 and between 119.76 +/- 0.05 and 239.73 +/- 4.86. In conclusion, the 17-MT feeding was found to have a greater effect on the growth, feed conversion ratio, masculunization and pigmentation of the electric blue haps than the 17-ES treatment.