Medium size Plecs: 6-10in

L200 and L128 both reach that size, they don't rasp driftwood much, but will use it for cover quite readily. Most plecs that rasp driftwood are going to also hit the 18" mark or more. All of the Leporacanthicus species would be good, also L66 L333 would be good. Depends greatly on what your preferences are. Narrow it down and we can help point you in the right direction.

heres a few i have on my comp that might work there are couple get a bit bigger (L14 and L24). Thefirst one is the L66 wyldfya said, but i prefer the one below that gets a bit smaller L260. the L200s and L128 are in this thread http://www.monsterfishkeepers.com/forums/showthread.php?t=27241 and wyldfya has a nice collection of L200s. there are probably a couple of hundred plecs that fit into that size catagory or a bit smaller so... worlds your oyster