Most just don't eat and can't get us to small tank. Most of the sweetlips, specially the clown sweetlips, need really large tanks and for the most part should be left in either the ocean or for public aquaiurms. They're also not very aggressive and in a close system like a tank they're easily bullied and get stress out which usally leads to them dying.
That's funny because most of the time you'll fine Pork fish kept in tanks with aggressive fish. They're similar to snapper as they're aggressive feeders and are consistantly swimming and very fast. I would say that you can keep them with aggressive fish and non-aggressive also.