Pond Boss Forums INTRO Questions & Observations Need help with new pond

I have a 5 acre pond in N. E. Fl. Jax area. It was finished in July of last yr. It is approx. 20 ft. deep. It is spring fed by numerous springs. Last Sept we put in 1500 Fl. bream and 500 channel cats. I have not seen the cat fish since. I did see the bream up until it turned cold. The had grown from the size of my thumb nail to approx. 3 inches in length. Now I see no sign of any fish. Nothing will hit fish food or bread thrown in. The pond has plenty of tad poles, bull frogs and little black water bugs. I have put in approx. 4000 minnows. Now I don't see any minnows. I have not seen any dead fish floating or otherwise. I did have some cormorants, until I ran them out. Do you think the birds ate all of the fish? Does anyone have any suggestions. The fishery where I am buying fish tested the water and said it tested good as far as ph and such.