I suppose, since he isn't light dependent, I could build a shelf of egg crate that covered the whole top half of his tank, maybe say 2 or 3 inches below the water's surface if he becomes a problem.
Or maybe say build an egg crate rack over half his tank. Maybe if they weren't on the sand he'd leave um alone. I got a feeling though that my hand is going to have to be in his tank almost every day after I start all that though.
Oh, well just a thought.