Some more details and more pics would help. How big is the plec? How long have you had it? If you can get a pic of the dorsal fin when erect, and a pic of the belly they may help. If not, at best guess I'd say you have a Pterygoplichthys joselimainus, although the colour is a bit off (but might be the camera).
See here and here for more info and photos to compare.