Hi, I bought these fish as M. callanois. Are they really cobalt zebra fish? I don't know the shape of the head stripes on the males or is it some kind of hybrid?
Cobalt zebra is a marketing name for Metriaclima callainos. Possibly some other things as well, but most often IME for Metriaclima callainos. Scanning through pictures of fish from the lake, they can have some barring.
Whether your fish are pure, IDK. But I would not rule out Metriaclima callainos because of some barring.