I had a very small Clown Trigger in a reef back in the mid 80's. God he/she was gorgeous! He was not vicious in the least, but he was extremely curious and had to just give everything he saw a little nip, as if to see if it was tasty. Christmas worms were too interesting so they had to be quarantined. On the other hand, I've read a few of the above posts mentioning Queens and an Undulate. I have not had a Queen because I know they are bad news, but I did have a spectacular Undulate named Attila the Hungary, he lived up to and beyond his name. As mentioned by others, he was a designer, if he did not like the setup of the tank, he would change it. He would pick up rocks and move them and set them down, back up, look at his work, then move in and adjust it a few times before being happy and leaving it. He was one of the most interesting fish I've ever had, you could pet him and literally lift him out of the water. If anyone other than me neared the tank, he would rush towards them and snap his teeth while changing his coloration to a darker green and brighter orange. You could hear the snapping teeth clear across the room. His favorite food, besides hot dogs and live fish (please excuse me, we were in college and he got clean seawater constantly so water quality was not an issue) was frozen peas. I would let them thaw just a little and then toss a few in the tank, he would take it in, mull it around in his mouth for a second and then spit out the pea with the outer skin perfectly removed. He would then just go ahead and eat both skin and pea. Eventually we donated him to the Waikiki Aquarium. They put him in a 400 gallon tank with a bunch of other aggressive fish. They were a little concerned that he was smaller than the rest of the bad boys but soon discovered that he cleaned out the tank. Eventually they moved him to the black-tip reef shark tank since they felt they could not dedicate a 400 gallon tank to one fish. He did not have the same experience in that tank. In short, Triggers are fantastic fish and loaded with personality, but each species and each individual is different, your mileage will vary. The biggest concern I have is not that they are mean or really want to eat anything in particular, but they have a tendency to use their sense of taste as one of their prime and first used senses.