i would say they are, they will only have fry if they feel safe and they will eat them to, if you want to save any plant up and have hiding places, also floating live plants are good as the fry hide in these, good luck
my tank has bot 10 good sized plats and i have a breeding box to cause i thought they were so gt it just incase the guppies seam happy i think i need a test kit to check the water as i just do water changes every other week and have never checked
my females always have the 'black spot' even when there not pregnant, it tends to go orange/red when mine are pregnant, are they fat
there is a picture of one of my pregnant guppies on my avie picture <<
a picture would help too
guppies should always have gravid spots (well at least the females) so they might nbot be preggy, the best way to tell is by how fat they get, when they look like they're gonna explode, you have babies coming your way