How about a Melanurus Wrasse? I have had yellows jump through eggcrate.. suckers hit that hole just right and still had to suck in their guts to get through but they did. They also will eat any oddball pests (may vary from fish to fish), especially helpful in a frag tank. Six Lines are cool but jump.. same with 4-lines.
http://liveaquaria.com/product/prod_Display.cfm?pCatId=2285
http://liveaquaria.com/product/prod_Display.cfm?pCatId=2285