In a 4ft community tank, I have had success only if the tank was heavily planted, with a stocking of 2m per 1f and a minimum of 12 fish. Fry fed off stuff which lived in the mulm.
In a 2ft breeding tank, plants help but stocking is not as important, I usually took 6 fish for breeding. Additional fry feeding was required.
A good food (for a couple of weeks) and a large cold water change generally kick them off without a problem. Fish have to be mature, of course, and this generally works only for the easy to breed species. If you want to breed more difficult species, you will need to get the water parameters just right.