I did say it was hard to say, but having lightened it up and sharpened it in Photo Impression, it looked more common plec to me. I'm rubbish at technical terms for fish anatomy, but it's dorsal doesn't look Parotocinclus, and the fin in between the dorsal and tail isn't quite right either. That with the shape of the head and pectoral fins made it look liposarcus to me, but again I'm no expert and the photo is very very difficult to judge from, although Himmel did say it looked like an identical but smaller plec to his/her other common.