Metriaclima Sp. Zebra Long Pelvic

[BJC787]

i got 3 of these given to be by a mate METRIACLIMA SP. ZEBRA LONG PELVIC and wondering how you sex them. they are about 3"
one is brighter than the other 2

 

[BJC787]

does anybody know

 

[synodontismultipunctatus]

as with most african im guessing its generaly aggression and colour for males, but you may want a second opinion