I'm thinking he's a male, although sometimes it looks like there is a little black coloration in the dorsal fin. All three of these pics are the same fish.
Definately a male festae. It's a festae because it's spot is about the lateral line which is the almost dead give away. Plus all the pearl in which most Uro's do not have as well as blue sheen on the face. It's a male because the lack of stripes and lots of pearl coloration. The most reliable way is that females dorsal fin will have a large black spot on it taking up half the fin and yours doesn't have it which means yours is all male.
Cool, thanks. TUIC has 5"-6" wild caught female Festaes at 50 bucks a pop. But mine is a youngster at only about 4 inches. He could get over matched, but I have extra aquariums if it doesn't work right away. Hmm, I have to think about this.