Channels would be my choice if you want a balanced pond. Blues are a predatory species. Once those blue cats get to 5 lbs say good by to everything else. They get huge and can be a blast to catch but will over take a small pond and eat themselves out of house and home. Be prepared to stock plenty of adult bream every year to provide forage for them.curious as to what kind of catfish did you purchase? I’m getting ready to stock my pond and haven’t decided between channel or blue. Right now I mostly have small bass.