mine is about 8 inches, I've had him a year and he hasn't grown. He is a very peaceful fish, and like algae although I did once see him eat a bloodworm. He's ONCE buried himself in the sand, but normally doesn't do that, and I had him in a tank with gravel for a long time and he was fine. They are a good indication of water quality, when the water is good, their tail 'whip' grows really long! When it's bad, it gets short.