I have a simple ebb and flow system with a 200 gallon fish tank and two grow beds totaling approximately 27 square feet of media grow space. Problem is that, although I've been told by everyone how prolific tilapia are, mine must be eating all their young because only a couple of newborns have made to past the fry stage in the year and a half I've had my system. I have white nile tilapia from a l…