I believe it could be a male especially if it is kept in a tank by itself? Females in large enough tanks don't usually present a problem unless holding eggs. Males on the otherhand are often belligerent among other males at least until dominance is established. The longer dorsal fin and anal fin of the fish in the photo seem to indicate a male as the fins on females,, are usually not as long. Males are often larger than females as well.
You may just have to try it with the female you have? If it is a male , and your other fish? is a female.. then it won't be long until they ,Ummm, get busy. It's what they do. If it is a female, then you will have a pair of females for an eventual male to coose from.
Hope you have plans for homing all the little ones that this species can produce in short order.