A Male has 6 - 10 stripes on the fins (look at the main large bands on the fins) along with larger heads, Females have 4 - 6 stripes on their fins....
I have kept Volitans with dwarfs trouble free, you have to make sure the dwarf is to large to eat, you do not want a tiny dwarf with a 8 inch volitan, they can eat them......... My dwarfs were mature before placing them with young volitans.
Kaye