Originally Posted by Austin8
I have had my guppies in my 29 gallon for a couple months with my gouramis tiger barbs and 2 silver dollars. They are get along very well. Actually better than I thought. The person who gave me my guppies told he they breed every month or so. I have kept an eye on my female and just nothing. Why isn't she breeding with the others?
Your Guppy's chances of breeding successfully aren't good with aggressive fish like Barbs in the tank. Barbs are "fin nippers" and will make a target of the male Guppy's tale. Any fish, with a large mouth will easily eat any Guppy fry that might be born. Guppies are best kept in "species" tanks or with very peaceful fish like Corydoras "the little cats".
I've kept Fancy Guppies in large, planted tanks for a few years and the adult fish may survive with larger, more aggressive fish, but they thrive in large, planted tanks and in large numbers of their own kind.
Just my experience with these fish. You're the tank keeper.