new to kribs

hi, I just got some kribs so I thought that I would join a mailing list and tell everyone. I'm sure you all are as excited as I am :). Anyway I also have some questions regarding my new fish. Of course I got them because I hope to get them to breed. And I have done a lot of reading on the subject, mostly online. But I have a few questions that I didn't really see any answers for so I thought I would ask here, sorry if they are childish or something. I have 2 pairs of kribs. They are both in a 45 gal European style tank(front bends out, giving a little more ground area, and a really cool magnification effect). I am pretty sure which 2 are the males and which are the females, 2 having non pointy back and belly fins, no fin spots, and yellow back with purple belly. The males having pointy dorsal and pectoral fins (I think those are the fins, always get fins mixed up) "eye" spots on there fins, orange and very little purple on the belly. The problem is that my females are larger than my males. The females are about 1 1/2 inches, and the males are about 1 1/4 inches. Also the females are a lot "fatter" I guess. I know I am supposed to buy them young if I want them to pair up, but I don't know how old these fish are, they are already very colorful, so I don't think they could be too young. Also the males and females don't seem to be pairing up, in the tank the male is usually hanging around the other male, and the female around the other female. So my question is: is this behavior just because they are fairly young, and do I have any hope of spawning them? Thanks for all the help in advance and I would love to hear about some of your fish tanks,