I have had successful spawns in a species only tank. The first spawn I had there were close to fifty fry but only 21 survived due to too many mature females looking for snacks for the pair to handle. I gave away the rest of the spawn along with the extra mature females and left the pair in alone in a 29g. Now I have three different spawns growing out in the tank along with two very fertile parents still looking for ways to spawn again. I have them in a well planted tank and I feed the fry freezed dried Daphnia and crushed flake. I have been getting spawns since November last year.