The Platy in question is about 6 months old, somewhat deformed (and I know the reason based on a previous question I had), in a 10 gallon with 2 other sisters and a snail at around 74 degrees, and has been pretty fine until now. I have performed a 100% water change recently, leaving the gravel and filter unwashed, and the other fry are still fine. I found it lying on its side but still breathing and barely responding to the net. Because I had put aquarium salt in the tank the mom and another Platy are in yesterday (because the mom is not looking too well either), I bagged the almost dead fry and after getting it used to the temp of Ray's (mom) 10g, I put him in, adding some stress coat afterwards. I did this about an hour ago, right when I found the fish on its side.
As stated, the other fish are showing no signs of stress and neither is the snail. Is there anything more I can do to help this fishy? Or is it too weak to go on?
Info on baby tank:
Temp: (was 74) 70
PH: around 7.6
Ammonia: between .25 and 0
2 Platy fry, 1 mystery snail
A Marineland filter (unknown as to which one)
Temp: 78 and rising (I'm stopping it at 82)
PH: hmm... 6.6
2 adult platys, 1 Platy fry
Tests used: API ammonia (NH3/NH4+) and PH liquid test kits