All you need is just 1 male and 1 female. Females will have an orange belly and males will not.
WARNING: Highly aggressive when they spawn so it is advised you keep them in a tank of their own. Once they breed, you will have to find a way to get rid of the fry, most fish stores won't buy them or give store credit so always have a back up plan.
Welcome to fishlore neil!!
Making sure you have at least a male and a female is all you have to do they are like rabbits of the aquatic world..and most deffinately they will kill/stress any other fish once they do start spawn mode ....good luck!
most convicts aren't very picky, and if you have a male and female it doesn't take too long.
other then that, keep water clean, and feed them goodies... EEEEE(goodies sound good right now...) i fed mine blood worms, meal worms, earth worms (didn't have black worms though ) and brine shrimp.... and of course flakes too, make sure there are places to spawn. (types of caves, plenty of flat surfaces, slightly hidden areas etc.)
best of luck and have fun. i enjoy watching my convicts do most of the work