All that is needed is a male guppy in with her.
it may be a femake or a FAT guppy
like human that is pregnant.
Because the guppy have baby inside it stomch
yes.
large stomach.
Your guppy will be pregnant if it has been in a container with a male since it reached maturity. A none pregnant guppy is an unusual thing. She will develop a belly and also when seen from behind she will have a dark spot visible deep inside her on either side of her vent. (the gravid spot)
Under normal circumstances every female guppy you come across will be gravid (pregnant). My advice is don't worry about it she will be pregnant.
It is probably excreta.
The average guppy is pregnant for 4 weeks! But they can b pregnant for up to 8 weeks at the most, one way to tell is to go to a local vet and check what stage ur guppy is currently in, or u can look up the stages online, it would help if u kept track of how many weeks pregnant she was!
1 to 5 to 40
it will have a red dot and black on its belly and will be fat