If the other fish are no threat to it, leave it along and see if it absorbs the yoke sack. If the company in the aquarium is threatening, could you put it in a breeder net? That might be good for it. Don't feed it until the sack has been at least partly consumed. And then watch it to see if it is indeed taking food.

That phenomenon is much more common with egg layers. In a few species that is routine (maybe to give the fry shelter in the bottom weeds and algae.) In some cases the fish will later absorb their yoke sack, fill the swim bladder (which allows fish to effortlessly change levels) and live a normal life for their species. Some will die. Some will remain "bellysliders" for all of their lives.

With a little help from an aquarist some bellysliders will survive in aquaria, whereas they would probably be picked off by a predator in the wild. Rarely are they bred on purpose.

Yours is a good question; these shorties are best asked as diaries. Like all of us as new members of GL, you haven't yet had a chance to distinguish diaries (which are quick and not-so-quick takes) and logs/ articles, which are supposd to be longer discussions on some aspect of the hobby.

That distinction need not be a value judgement on what is asked - though "Is my guppy pregnant?" is rather over worn. ;) (Answer in most cases, "Is it female?")

We're glad you are here.