My 6" Asian BUMBLE-BEE catfish swallowed overnight my 4" baby South American MARBLED-ACHARA catfish, which in the wild can grow up to 36". One expensive meal and totally my fault. Took for granted how wide he could open his mouth. He was rocking like a see-saw on his belly the next morning at the bottom of the tank. To answer your question, I like feeding them anything that sinks like Hikari carnivore pellets, Wardley shrimp pellets and spirulina discs.