Artificial Incubation, Hormonal Sex Reversal Promoted Tilapia Boom

Research And Development Expansion of tilapia farming on a commercial scale was hindered by the limited availability of quality fry realized by researchers. Attempts were made to develop a practical technique of massscale fry production at the Asian Institute of Technology (AIT) in Klong Luang, Pathumthani, Thailand. A series of onstation trials were conducted over a decade, maintaining the Chitralada strain of Nile tilapia broodstock in hapas installed in earthen ponds. Breeding in hapas made the collection of eggs easier at early stages, which is needed to segregate them based on age. Uniformity in fry size and age in a given batch ensures that all the fry receive an adequate amount of hormone through feed, thereby resulting in a high percentage of males at the end. The AIT method includes techniques of maintaining large number of broodfish in hapas in earthen ponds, egg collection at fiveto seven-day intervals and artificial incubation of the collected eggs in a clean and controlled system. Feeding methyltestosterone hormone mixed with fishmeal at 60mg/kg for 21 days ensures over 99% males in the fry population.