That�s a lot of Tilapia for your pond, but I would bet that they won�t do any real harm at that level, unless you already have too much biomass or other O2 problems. If your water falls much this summer, you might have an ammonia excess, but, as Einstein or somebody said, �It depends.�
Regarding food, Tilapia are mainly vegetarians. They have pharyngeal teeth with which they can grind vegetable matter. In addition, they secrete a layer of mucous which traps phytoplankton in the water which flows over their gills. They then swallow the mucous and plankton. Hatcheries typically feed Tilapia with catfish food, and they will mingle with the bream and gobble floating food in your pond, but not quite as avidly as the bluegill, at least in my experience. They will sometimes eat small fish, bugs, worms, etc. Last year about a half-dozen of mine were caught on worms and, especially, crickets. Two or three were caught on small plugs. All were released. This year, I had an �extra� 5 lb. put in so that about August I can catch a few for the table.
I am trying a sneaky experiment. When I feed the bluegill, I throw out a few handfuls of whole kernel corn. I can�t see through the bloom to know if the Tilapia are eating it, but I hope they are. Around August, I will try a kernel or two with a hook in it. I liked the suggestion made here of using cabbage, but summer cabbage is not all that cheap around here, and it is hard to throw it very far�unless you throw the whole head.
Incidentally, I requested to be first on the Tilapia delivery list and got mine about April 21. Water temp was 72 degrees at the time, and I put in a little over 13 lb. of T. nilotica per acre. They have done such a number on the filamentous that it never got a strong foothold and is only present in islands less than a foot in diameter and mostly attached to rocks or brush in very shallow water where the Tilapia can�t get at it. This is despite heavy fertilization and a great phytoplankton bloom. Every year previous to this, there were mats of filamentous everywhere. I do a lot more fishin� and a lot less cussin� this year.
Lou, 13.5 acre
