Ive actually got them in a marine styled tank with the whole back ofbthe tank is the filter, the back 4" right the way across the tank is all sponges. Do they like calm water with very little movement or does that not matter??
There are more than the one way of sexing the fish, i.e the shape of the body, the shape of the forehead etc..... plus the aquiaum that i bought the fish from also helpped me to sex them, the guy that owns it has been in the business all his life and knows a hell of alot. And also a friend so i trust him opinion.