Here is an updated pic of my managuense. It's 4" now and very active. Just throwing this out there again to get people's opinions on sex now that's it's getting a little bigger.
It was about 2.5-3". Chose this one because there were 6 of them in a tank at my LFS and the rest were all up in the corner beat up and this one was swimming around and kept chasing them lol.
I know it's hard to sex these fish young but I'm looking at trying to get a pair and I don't wanna put the wrong sex in with this fish. This picture it is in its new tank with darker gravel then the picture above
I say male. I've got 5 (2 breeding pairs and 1 lonely girl) they can change very quickly and fool you, but judging from that pic I would say definately male.