Male or female ?

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There is a lovely female guppy
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A beautiful male guppy
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If you keep males and females in the same tank, you will have babies. If you want babies, put a ratio of 1 male to every 2 or 3 females. That way the male will not harras the other female guppies.
The male has a modified gonopodium which he fertilizes the females eggs with. They will hatch inside of her and be born fully formed! They have a much better chance of survival in the community tank because they are born larger.