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Let me put it this way. The chances that she is
not pregnant are vanishing small. These fish have but one mission in life - to produce fry as often as possible.
So if she was with males at any time after she was sexually mature, she will have mated and from just one mating she can produce fry for months & months & months to come and given a little time, she’ll mate with her own sons if she has no other choices, once they are old enough. Only one has to survive long enough for that to happen.
She will undoubtedly get bigger & bigger and in a few weeks there will be fry.
In fish this colour the gravid spot is usually not visible and it doesn’t have anything to do with pregnancy anyway. It’s there even in virgin females.
It gets bigger in pregnant fish because their skin has to stretch to accommodate fry, so the gravid spot does enlarge during pregnancy but only because the skin stretches.
The gravid spot can’t be seen in a lot of the colour morphs of various commercially bred
livebearers, including those that are black, yellow, orange, white, etc.