Hmmm that's a hard one. "She" looks like a young male...the fins look too long. Females can blow bubblenests too so that doesn't determine anything. I guess you'll just have to wait to see if "her" fins grow or not. How long have you had "her"? Gorgeous fish by the way!
I'm pretty sure that is a male. I don't see any egg spot and he's got a male shape.
I wasn't sure because of the stomach (almost looks like an egg belly, but could be bloated).
petco sold the fish as a female...haha didn't think they could mess up something as simple as telling a fish's gender.