heat is what you need for tilapia (they are tropical fish and love heat)they start dying when the water dips below 57 degrees. Damion at americulture is raising 1 pound of tilapia per gallon of water with his filter system. You need to try and use all males the females have a low weight to feed conversion (unlike our american girls) compared to males. The aquarium at las conchas raises tilapia in salt water so it could work. Also medicinal herbs are huge in mexico and easy to grow.