Those just might be alien fish,, you see any place around there where a spaceship might have landed?
That being said, we had a little bait pond where we were trying to grow goldfish for river bait as they can be expensive to buy a lot of good sized ones for trotlines and bank poles. they multiplied and grew quickly, exactly as we had anticipated but as you said, were almost impossible to catch with a net, we tried all kinds of tricks, including dropping an umbrella net under water with a hoist system, then feed them above it on a regular bases and then when we needed some quickly hoist the net and were not successful enough to supply baits for us, we wound up completely scrapping the idea and switched to to a different kind of fish to use for bait. some of these that survived the sun perch grew to be 2' long or better.
