Credit: Manuel Cano Alfaro (Guatemala)
The first photo shows people collecting the swim-up fry of Nile tilapia (Oreochromis niloticus) from the spawning tanks. Tilapia broodstock are stocked at the ratio of four females for each male. The collected fry are passed to the sex reversal unit which is shown in the second photo. The sex reversal of which targets the production of all-male tilapia follows the established procedures whereas fry are fed on powdered feed containing the male hormone (17-alpha-methyltestosterone) at the concentration of 30mg/kg of feed for 22 days.