Thanks Blert,
Indeed, my experience has been that they constantly "book" or hunt for food throughout the day and throughout the gravel as well -- but since putting in some large decorations (well, really one large one, a "tree stump" piece picked up at Petsmart), it seems there are a lot of hidden pockets and places for food to get caught. I noticed this yesterday when I was doing some re-arranging of the decor and gravel and that kicked up a whole bunch of nasty stuff that the one Black Moor didn't find beneath the substrate; I did a small water change and gravel vac after that (the tank is still cycling), but I figured a catfish would help with this...
It's interesting that you say goldfish may be at a risk with certain suckers while some are saying that Plecos, etc. would be fine...I don't know who to believe...