Umm I hope you people who are saying that he needs tank mates are kidding!!
Nice looking rhom though, I love the yellow color on him. People have high expectations for Ps and generally end up dissapointed with them. Give hime time though. It can take months if not a year or more for a P to become comfortable and "come out of his shell" so to speak. I have an S. Maculatus that was very shy for several months and then it was like a swich was flipped and he turned into the finger chasin, glass slammin, hand feedin beast he is today!