phillkg,
You can catch him without tearing the tank apart. Know where he sleeps. Go to the tank in the very early morning while it's dark. Turn on all the room and tank lights at the same time. He will be blinded temporarily, and you will have the upper hand for a minute or so. Position the net in front of him and poke him from behind with a turkey baster. He will swim forward. If you miss him, keep after it. He'll be unable to see the net very well for a minute or so. I caught a 5" tang on the first try with this methood.