Sun catfish is probably your best Bett for a predator, 4-line pims are aggressive to one another so you will need a group which I think will turn out to be to much once full grown for a 180, they are also not the most predatory cats but will snack on meaty foods if it fits in their small mouth. I will say they can handle their own with SA fish, I had two that did very well with a large jag, midevil, butti, an exceptionally aggressive Oscar, and a wolf who occasionally took chunks out of them but they'd heal fast. They'd fight back till the other fish got tired if need be, needless to say they are great fish, and I am thinking of starting a smaller set up to grow some out with some other fish I have. I also had a big leporinus take a small chunk out of one of them. They fought too. It was an aggressive set up, everyone was 8"+ the smaller pim being the smallest fish at 8 inches. The rest were more around a foot. Also if there's a significant size difference between two specimens expect one to get beat up time to time by the larger one to keep the smaller one in check.