Credit: Muhammad Shahid Iqbal (Tawakkal)- Pakistan
The masculinization of the fry of Nile tilapia (Oreochromis niloticus) –as shown in the photo- is done in 5m2-hapas placed in earthen ponds. In order to judge the age of fry, only fry hatched from collected eggs are used in the sex-reversal process in which the male hormone 17 alpha methyltestosterone is used. In the particular facility, the dose of used hormone is based on the quantity of hormone used to the number of treated fry; (5g hormone for 500,000 fry). The duration of treatment is 21 days. Each hapa is stocked with 30,000 fry. The hapa cover protects tilapia fry against possible bird predation.
The facility may nurse tilapia fry up to 5-g fingerlings whether to be stocked in the grow-out ponds of the facility as well as for farmers who demand bigger size fry. It may worth mentioning that almost all fish farmers culture all-male; sex-reversed tilapia fry.