Guppies are also easy to breed, in fact, so easy that they are open mass produced as feeders for other fish! One of the main thing to lookout for when breeding guppies is that there must be plants for the fry to hide. Unlike bettas (fighting fish) that gets protection from their father, guppy fries get eaten by their parents. If you have a bunch of guppies but you never had any fries, it is not because they did not breed but rather, the fry got eaten before you know it.
Guppies are selectively bred for their colours(and patterns) like show bettas are but they have an advantage over bettas that adds to their popularity, that is they are community fish and can live in harmony without killing one another.
Males have longer fins than females. Sometimes people get confused when they see the long tail fin they subconsciously look at it like a dress and think they are females. Actually those are males! (In fact, most fish species have males looking more beautiful and colourful and with longer fins).