Nice!
Mine has been growing very slow also. Got him when he was well under 2", now, nearly 2 years later, he's just under 5". I almost lost him in the beginning. I didn't yet have an intake guard on one of my canister and he was sucked into the canister. He was in with a bunch of other much larger fish, so I figured he was eaten or something. Luckily I decided to clean that particular canister that weekend(5 days later), because when I opened it up, the little guy was swimming around inside in an inch of water above the filter pad. The canister is rated at 700hp and luckily has the pump on the bottom.