The Red devil in top picture we thought was female... so we put it with the guy in 2nd picture..they started fighting and we separated them with a screen... now the one who never had a hump on the head {that we thought was female has now got a huge hump..so i thought because of the humps they were both males??? So this may not be true... I could get a picture of vent and see if you could sex them if that is the only way to know for certain.. we have them in a 75 gal tank.. and thank you everyone..glad you like them..