Get all males. Sell the females back to the local fish shop if you like or euthanise them if you can't find them homes. DON'T EVER EVER FLUSH FISH, NOT EVEN DEAD ONES! By doing this you introduce new fish into waterways in areas where they don't belong, along with any foreign bacteria they may be carrying, and this can decimate native fish, bacteria, whole ecosystems.
You are fighting a difficult battle here because female guppies can be born pregnant!
Best way is to only get males. They are the most colourful and pretty ones anyway! The easiest way to tell the sex of the fish is to look at the anal fin (last fin underneath before the tail). In a male, that fin will be decidedly spike-shaped, and in a female it will be a more rounded, fan shape. A pregnant female will have a dark spot right in front of that anal fin (see picture). That dark spot is the heads of the fry you are seeing. However if you don't want lots of guppy babies, and you do have pregnant females, I wouldn't worry too much, you don't need to do anything as the guppies will quite happily eat the fry.
The lower, more colourful fish is the male - look at the shape of the anal fin. Notice the dark egg-spot on the female, and the fan-shaped anal fin.
You are fighting a difficult battle here because female guppies can be born pregnant!
Best way is to only get males. They are the most colourful and pretty ones anyway! The easiest way to tell the sex of the fish is to look at the anal fin (last fin underneath before the tail). In a male, that fin will be decidedly spike-shaped, and in a female it will be a more rounded, fan shape. A pregnant female will have a dark spot right in front of that anal fin (see picture). That dark spot is the heads of the fry you are seeing. However if you don't want lots of guppy babies, and you do have pregnant females, I wouldn't worry too much, you don't need to do anything as the guppies will quite happily eat the fry.
The lower, more colourful fish is the male - look at the shape of the anal fin. Notice the dark egg-spot on the female, and the fan-shaped anal fin.
