Hello, I just acquired a Harlequin Tuskfish. It is about 4 inches and supposedly about 6 years old. My tank is 45 gallons. It is the largest of my 4 fish for sure. The others are a coral beauty a midnight clown and a golden sailfin blenny. I was told he probably shouldn't get any larger so he would be fine in my tank. He is eating very well and he is very active. Is this ok to have this size fish in my tank as long as it doesn't get any bigger?