Jasonmo928, I cannot directly answer your question, as I have never tried that approach. A single bluegill, properly fed, will grow to about 10 inches. They are EXTREMELY territorial when mating (not a problem with only one), I do not know how bad they are other times. A crappie (also known as a Calico Bass) might work as well, although they grow slightly larger (not as large as a bass). They are in the family Centrarchidae, same as the bluegill. They are quite active in the winter, being a popular ice-fishing quarry. The good news, if it does become too large, they are considered one of the most delicious native freshwater fish in America.
I have a pond half the size of yours with about half as many fish. I too have a number of fry that survived past the fish food stage, fifteen last year. I decided to give most of them away, until that is, I actually tried to net them. The first one took about ten seconds, the second one about a half hour. I did not catch another one for about two weeks. Anyone who thinks goldfish are dumb or have a short memory should try netting a second one in a pond full of plants.
I have more fry again this year, still very small. I do not know how many will survive, but they will have to go. I will probably net them very early next spring when the water is still cold and there are no plants in the water. I do though have concerns about stressing the fish at that time of the year.
A heron took a few this spring, but is also took a few of the adults. Now if I could only teach the heron which fish it can eat, problem solved.
Another idea I had running around inside my head was to place a large screen or net of some type on the bottom of the pond, with line tied to each corner. After a few days (or how ever long it takes) when the fish become used to it I would feed them over the net and then quickly lift it. It all sounds too easy, I am sure.
Good luck with whatever you try.
Perhaps you could even trade?
