Live-bearers....Guppys, Mollys, Platys, etc. You already have cichlids.....a pair of Jewels will yield about 300-400 fry every MONTH compared to the Convict which breed as frequent but only produces 40-100 per clutch, mine only do around 60 atm. My Jewel fry are only 12 days old and eating crushed flakes already, the previous are 1 & 1/2 months and are 1/4" and starting to look like their parents already. Growth rate was more than twice of the Convicts at the same temp; 78F
EDIT: I like the ornate as your avatar better, dude