As has been suggested by others ... Prime or Amquel+ along with daily PWC's is in order ASAP.
As Shawnie mentioned, if you can find - or order online - Tetra Safe Start, that is the bacterial additive you want to use to cycle a tank ... and would help quite a bit. If you pick some up, make sure to follow the directions to a T.
If the fry drop ... the Prime or Amquel+ w/ daily PWC's is the way to go with the little ones.
Lastly, it's always a good idea to have some meds on hand. I have a livebearer community (all male), and though I haven't had to medicate much at all ... I have had a couple of fish I rescued that had issues, and used Pimafix/Melafix combo in my
QT as both a preventative and/or a lighter form of medicating. Of course, I also employ frequent partial water changes (PWC's), as clean water is of the highest importance concerning fish health.
If the fish won't eat and thus aren't taking in vitamins and getting nutrition ... a supplement like Vita Chem can help.