i was in the same boat at the tender age of 16 when all i had was a 120 the folks bought me and i couldnt keep up with costs soo i sold the present fish and left the tank for a while, i then saved a bit and bought myself some kigoma frontosas froma few different people and before you knew it i had myself a colony the gives me around 30 fry every 2 months and i sell out the kigoma fry for 5$ at 1 inch 10$ at 2 inches and there is always a market for kigoma in my area and worst case senerio i sell to big als and they do the rest bottom line to make money you need to invest regardless of fish you want to breed, if i were you id find yourself a rare fish where you can for sure turn profit and start off there, try beta fish theyre relatively easy to breed and lots of people buy them lol