I had a royal gramma that used to bite me all the time. He never learned the hand thing. He'd just go hide until I started focusing on whatever I was working on, then blammo! he'd bite me again. Little bugger.
You could always do the PVC on a string route. I have a piece of 1.5" PVC that I have attached to a string outside the tank. I use a rubberband to hold the nori on. I get it all assembled adn then put it in the tank. Then take the PVC out when they're done. I have a feeling if I was attaching the nori inside the tank I'd end up with bitten hands too. Its like a feeding frenzy when the nori is introduced
