Mine has never nipped at any corals. It is my favorite fish. He is a bit agressive at feeding time. He tries to steal from my clown gobies or chase them off, but they always get away with no problem and they are allowed to get plenty to eat too. I've read that they can attack and kill gobies, but I've never had any physical contact between them. They definetly can be jumpers though. Keep a canopy or covered top.