Join Date: Oct 2010
Location: Victoria, Australia
To answer your questions about killifish, I've never had them overpopulate a tank like guppies or some of the other livebearer species would. The adults tend to eat any fry they see, and once you reach a certain number of adults, the tank has to be very heavily planted for fry to survive.
I see Fundulopanchax gardneri at many fish stores here in Australia, but I'm not sure if they are something PetCo would stock.