Sexing Opalines....i May Have Bought Two Males

[matchstickman47]

both look exactly the same and are overly agressive

 

[mixmaster jay]

both look exactly the same and are overly agressive

Males have a pointy dorsal fin. The dorsal fin of the male tapers to a point, whilst the female will be fatter in the body with the many hundreds of eggs she is carrying.
I hope this helps you

JAY