That's true. Though another option other than catching them is that near my house they actually have a big breeding pond that sells to locals to stock their own fishing ponds--So they sell all the big mouth bass, catfish, etc. Though I guess I don't know if they would sell just one, most people buy 100 or more haha!
I do looove the look of the channel catfish, but they do get large. Like 3-4 ft long. Which sounds incredible, but not in a 5 ft pond. :) I think the bullheads sound interesting, the black bullheads get 6-10 inches long with 15 inches being extremely rare. Some people were saying they struggled keeping them alive longer than 3 years, which is a little disappointing. Yellow bullheads have a 7 year lifespan which is a little better.
My worry with mosquito fish is how small they are. I kept hearing warnings that they would be goldfish snacks!
Though I could get a smaller fish species for the top half of the pond above the water fall. I was looking at longear sunfish and they are pretty!