Im going for guppy’s...Guppy’s tend to breed whether you want them to or not and can breed in some pretty appalling conditions (not that you'd want to have appalling conditions in your tank, anyhoo.), since I stopped using breeding nets many months ago, and haven’t really bothered to set up a fry tank since I got my house, I’ve found that guppy’s are by the most successful breeders- the platys are good, but they tend to eat their fry an awful lot, while as I always find that in a large batch of guppy fry you will always get a couple of survivors.
Molly’s can produce huge quantities of fry, but they can be slow breeders and have one of the longest pregnancy times for livebearers plus their fry can take over a year till they are full grown- molly’s also chow down their own fry like there’s no tomorrow given a chance and their fry often die when they don't have enough room to grow...
Either way though when it comes to breeding any fish, make sure you have space for the fry as they mature and somewhere for them to go to when they grow up, with fish like guppy’s its easy to get over-run with them they are so successful at breeding.
