>>> don't nip like other barbs
Most barbs are perfectly peaceful. Unfortunately, the commonest available, Tiger Barbs are aggressive. People tend to assume all barbs are. I have kept over 100 species of barbs, and could count on the fingers of one hand those which were at all aggressive.
Cherry barbs are a non shoaling species best kept as a pair, or trio, 1 male, 2 females. 2 males together may fight amongst themselves.
Pictus catfish have large mouths and are fish eating predators. It is what they do. They are not aggressive, but will eventually eat small fish that they can swallow.