Looks like an L114 Pseudacanthicus cf. leopardus to me; I'm pretty sure they can get up to a foot in length, and, as most Pseudacanthicus species are, pretty aggressive with other plecos. Could also be an L600 (Pseudacanthicus leopardus); I believe they're the same species, except the L114 has a lot less orange, supposedly a flatter body profile (Although I don't really know if that's true), and larger "spots" on their head.