Stan's right. It is a species of armoured catfish (yes, I did spell "armoured" with an "U"...I am Canadian afterall

)
More specifically, I'm pretty sure it is a species in the suckermouth catfish (Hypostomus plecostomus) group, commonly called pleco in the aquarium trade. But I don't think it is Hypostomus plecostomus...but rather some other species in the Hypostomus genus. Maybe Hypostomus nematopterus?
Or maybe it is in another genus. Maybe Squaliforma villarsi? Or a Pterygoplichthys species?
Not too sure...don't know too much about armoured catfish indentification.
If you want to decide for yourself, go to PlanetCatfish.com and look under their Cat-eLog. They categorized catfish with a "L" number...and I have narrowed down to:
L060: Hypostomus nematopterus (close...but tail spotting in the reference picture are larger than in your picture)
L093: Squaliforma villarsi (but body spotting in the reference picture are larger than those in your picture)
L130: Hypostomus sp. (Body spotting and blotching looks right, but the tail is more forked in the reference picture than in yours)
L347: Pterygoplichthys sp (This one is pretty close too...)
Maybe post it up on PlanetCatfish and ask the experts there
