As to your question of the breeding habits for channel catfish, I believe that the catfish need at least a large cave of some type. In the wild they tend to pick out hollow things, (logs, tires, underwater caves, etc.), LARGE plant holders may work (found at any respectable flower shop or your local hardware store), and the male and female will do their thing. You can tell breeding males from females in which the heads on the males look swollen in comparision to the females. This is to help the male block the entrance to the cave better, so other fish, such as bluegills or whatever else, won't be able to sneak in and eat the eggs/fry. But with that many fish in your pond, it's likely that the other catfish will eat the fry as soon as they gain independence from the male guarding them. Hope that helps.