Over the past couple of years scientist have made it possible for Tilapia to grow larger and mature faster. They also made it possible for the fish to survive and a lower quantity of food. When the Tallis are born they are gender less. The amount of testosterone or estrogen they have flowing through their bloodstream determines what gender they will become. Farmers are now feeding the Tilapia with a food laced with masculizing hormones so the fish will be males. It is not clear when this gmo came about but we do know most tilapia farmers have been doing this for years. Why you may ask because it doesn't add anything to how the fish lives it just helps farmers because female Tilapia are known to be smaller which means less money for the farmers. Some pros bigger fish, more money for farmers.nothing is put in the fish to effect the meat we eat. Cons well there aren't any other than there are less female Tilapia. I am all for this GMO because it isn't harmful to the people or environment.