Dear all, We all know the importance of sex control for tilapia production in the majority of the numerous farming conditions of this species group. It is not necessary to remind you all that numerous techniques have been used up till now (hybridisation), or is more classically used for sex control such as manual sexing, hormonal inversion and use of YY males. Each of these techniques has been often discussed showing their advantages and disadvantages. We all know farmers who use one or another approach depending on his constraints which are essentially the cost, the facility for its use and its efficiency. However, it is harder to have a relative estimation of which farmers used which approach. Would you share this information telling us if you use mainly a) manual sexing, b) hormonal inversion, c) off-springs of YY males, d) hybridisation, and mentioning which rearing conditions you are using (monoculture, polyculture, extensive or semi-intensive conditions). Or do you use predators and if it is the case which species do you use (Hemichromis, Heterobranchus, Clarias, Lates)? Finally, what is the main justification of your choice? Thank you very much, Helena D'Cotta and JF Baroiller ___________________________________ Dr. Helena D'Cotta CIRAD-PERSYST Aquaculture Research Unit, TA B-20/A, Bur.A18 Campus International de Baillarguet 34398 Montpellier cedex 5, France Tel : 33 - (0) 467593951; Fax : /3825 dcotta@cirad.fr http://aquatrop.cirad.fr/