They don't get very big, right around 5" though people say they are aggressive fish, they aren't really if you have fish in the tank that are bigger that it. So you wouldn't want to get a six line wrasse, which would become food. They can eat fish up to 1/2 their own body size. They can be hard to start eating and will have to be weened off live food in most cases, but you can simmulate live food with a feeder stick.