Not a bad idea...
I wondered if it got too cold here for catfish, but then remembered the bullheads in Minnesota.
I'd probably have to mail order something. Fish stores tend to stock less hardy varieties of things. Every snail I bought there died, but the ones I fished out of the creek here have thrived, and are on the verge of developing a rudimentary civilization. They, and the crayfish, are one reason I don't want to poison the algae.