I've always had one in my tanks. In 7 years I've had two and the first one "got lost" in a big tank swap I did a few years ago. I know he made it into the new tank but after a month or two of not seeing him I went ahead and got another. I have LPS, SPS, inverts and a mean Clarkii and it hasn't posed any problems. They are small but brave and I never have any trouble spotting him since he's always swimming a few inches away from cover.