What kind of structure do you have in your pond?
Not much other than some downed branches. I'm in the process of expanding the pond and will certainly be adding additional structure when I deepen the other half.
My Channel Cats are reproducing in my pond probably because I dumped several dump truck loads of pipe chunks into the pond in various places, i put it in there for structure and cover purposes but obviously some have landed probably with mud in one end that is giving them nesting cavities.
I like your pipe idea! Better than 5gal buckets I think.
What I would guess they may be mud cats that have found their way into your pond, other than that, the difference in growth rates of the fish I stocked in my pond really surprised me. some of the same CC that I stocked, some seemed to grow literally twice as fast as others.
I'm pretty sure there's no fish in there that I didn't add or didn't know about. In fact, the pond dried up last year during our drought, yet somehow a couple of bass and bluegill survived in about a hot tub amount of water. When the pond filled back to the halfway point is when I added the fish.