Lol, well if it puts your mind at easy I've never had trouble with a betta getting stuck under anything it couldn't get out from under/behind in the three years I've been keeping them before....generally they're a little more capable then we expect, lol. But I did a water change and moved a couple of things today, and didn't properly secure the heater(one of those pad-shaped heaters)so there was just this itty bitty gap between it and the wall down by the sand. Its possible with enough wiggling he could have got himself out on his own, but I figured I'd help him any way and then made sure he couldn't wiggle himself back in there. xD
Hmm.....maybe if he was more white, Inuyasha could work. xD He has the energy, not quite grumpy enough though....