Aquaponic Pond fish

My son and I went over to our local neighborhood pond with a small fishing pole and a can of red worms. we caught 9 fish for the aquaponic garden. the fish were sun perch and bluegill. We used number 10 mustad hooks and a bobber. Today I noticed that there were only 2 of the minnow type fish we had netted in the pond. The day before there were about 30 of the little fish. I guess perch eat minnows.