Breeding your pet can sometimes be tricky and in order to increase the chance for them to spawn and obtain next generation of fry, basically there are few things which you can follow. First, ensure that your aquarium environment is suitable meaning that there are lots of live aquarium plants to enrich and improve water quality to crystal clear condition. With dense vegetation this also serves as a good place for your fish to lay eggs and for the fry to hide from predators. If your aquarium is infested with small population of aquarium snails, I would suggest you get rid of them because the snails will easily search out all the eggs and make a good meal out of it. This goes the same as well with all the catfish family like pleco and corydoras catfish.
Second, you should ensure that there are at least 10 – 20 of these little fish living in a group and the more they shoal and mix together, the higher chances to have them ended up mating. There is also another way suggested by some aquarist in which they find that dimming the aquarium lighting way below normal level will help to stimulate spawning, however I don’t really find this to contribute or make any difference to increase chance for them to mate and breed.
Normally, in a single successful spawn, a female neon fish can release more than a hundred eggs and it is not common to see low mortality rate due to cannibalism. The size of a young fry is so tiny that sometimes you may even find losing a few when changing water and therefore extreme care must be exercised so that you don’t ended up accidentally sucking out and removing them. If possible, provided you have extra tanks, you should move out all the adult fish once you start seeing little fish fry appearing. To feed them, you can consider using some cheap aquarium food supplies like microworms and powdered flakes once they start searching for foods.