Hormonal sex reversal technique of Oreochromis niloticus larvae in a tank in the Urban Commune of Kankan, Republic of Guinea

Hormonal sex - reversal is widely recognized as having significant advantage over both manual sexing and hybridization. The present study carried out in the aquaculture center of Kankan aimed at producing monosex male fry of Oreochromis niloticus in order to increase the yield of this species. During this study, 95 Oreochromis niloticus broodstock including 21 males and 74 females were paired (spawned) in a spawning tank of 135 m2 surface for 15 days. The respective mean weights of the spawners were 448.6 ±157.7 g for males and 406.7±115.9 g for females. Hormonal treatment was performed on 900 larvae with an average initial weight of 0.028 g from the 10th post fertilization to the 38th day in a tank of one (1) m3. The larvae were fed with 1 kg of imported "Raanan Premium Fish" powdered feed titrated with 40% protein, mixed in a hormonal solution containing 17-α-methyltestosterone and 90% ethanol with respective doses of 100 mg and 500 ml. At the end of hormonal treatment, 578 fry with a final average weight of 4.5 g were conducted in a pre-pregnancy tank with a surface area of 50 m2 for 30 days and yielded at the end of pre-pregnancy 501 fry with a final average weight of 13 g, a daily growth rate of 0.22 g, a specific growth rate of 1.7%, a survival rate of 64% and a mortality rate of 36%. After sex identification (sexing), the rates of hormonal treatment were 83.33% and 16.66% for males and females, respectively. In conclusion, the popularization of the results of this study could be considered as an alternative for a production of monosex male population in Oreochromis niloticus that will feed the networks of local producers to improve the production of the species throughout the country. Keywords: Oreochromis niloticus, hormone, sex, larvae and tank