I've read that too. No issues with my lionfish and the Niger trigger in ~7 months of them being in the same tank. The shark will be a new venture though. I'm thinking a trigger's tendency to nip has something to do with their dominant status. My trigger is down pretty low in the rankings, so that may be why there hasn't been an issue. Just a thought, but I'm sure that has something to do with any signs of aggression.