Bigger tank! ASAP
Change water daily, 80%, conditioned.
Feed very sparingly until you get a new tank, vacuum uneaten food and poop with a turkey baster daily.
Do you have a filter?, airstone and pump?, anything to at least circulate the water to oxygenate?
Oblio's link gives you a lot of information from the size tank they need to the water hardness they need.
Judging by the photos, you have one male and two females. These fish are called livebearers; the females keep the eggs inside their bodies until they are ready to hatch. They give birth to fry roughly every 4 weeks - lots of fry. You need a big tank for all those fish!