Liz, I love the pattern on that spotted ralph. Nisce costatus as well.
My new guy is an Orinocodoras eigenmanni.
Here is the planet catfish article on it..
http://www.planetcatfish.com/catelog/species.php?species_id=612
At first they look similiar to striped ralph cats. When you compare them. the orinoco is quite different. They tend to be more black, have a longer snout, marbeled belly, larger adipose fin and reportedly get 12"!!
Not a bad pick up for $4!