Hi Hannibal. I have a 10 gallon tank for breeding (only one pair), In a 75 gallon tank you can have up to 5 pairs of Apistos, but you are going to need many caves, I use coconut shells as caves, it looks really natural. Another thing to take under consideration is the fact that different species within the Apistos family cannot live together in the same tank. you may have to do some research and figure out which kind of species could co-exist in the same tank.