M. johannii females and juveniles are yellow/orange. M. cyaneorhabdos male and females are both blue. Odds are if you have a group that is all blue, they're M. cyaneorhabdos. These appear to be rather small, if they're under 3", you can be pretty sure they're M. cyaneorhabdos.
+1 to what Joea said, he really knows his stuff and judging from the size these appear to be they are Mainganos. Really just wanted to tell you Yellow Labs and Mainganos are my favorite mix. I like them better than P. demasoni for the blue addition to the tank...Good choice!