Hi RM,

It all depends on your goals.

If you want a lot of bass, the cats will compete with them. You can have both, just not as many of each. If you don't favor 1 over the other, keep both! Cats tend to stir up mud, but not real bad.

Your little grass carp will eventually get big, and they can root and stir up a lot of mud. As long as he is not stirring up enough mud to be objectionable, keep him. He will help keep the weeds down somewhat.

Welcome, and hope that helps a little.