I had this happen a long time ago, so I know it is possible......but when exactly do guppies have the ability to have babies? I have guppy fry about a month old and I am already able to tell which are boys and which are girls 'cause I can see gravid spots! I remember a long time ago, I had a baby fry have tiny tiny (on accident, didn't know she was prego since she was so small!) babies.......which took forever to grow up since they were so small to begin with.....I am talking the size of the head of a straight pin..............little little. It seems as though they are "born pregnant"!