For a start, the tank looks too small for breeding much of anything. I'd recommend at least a 30 long for a pair, 40 breeder for a trio. Average spawn size for a young female is 50, up to 100 for a large, mature female, amd once they start they'll keep at it for a number of broods before taking a break as long as they're fed and maintained properly. IME it's best to leave the fry in the tank until they reach at least 1", and a couple growing broods will overcrowd a small tank much too quickly.
Otherwise, good filtration amd fast-growing live plants (I use Najas and duckweed) to help maintain water quality between changes. I feed mine NLS Grow pellets as their staple diet, occasionally spirulina flakes, and canned green beans once weekly to help maintain their digestive tracts. Other veggies are also usable, but with multiple tanks full of them the canned beans are easier to work with. French cut are best, they sink on their own and are usually completely gone by the next morning, any leftovers by that evening.