Temperature up to mid 80's and some good old salt should work
I’d try some seachem paragaurd. Keep gravel vacuuming and doing ur water changes.
There is no point to putting them in a quarentine tank, because if one is exposed, all fish in the tank are also exposed..
The entire tank must be treated.
I treat with 3 lbs of salt per 100 gallons, any less the ick will not die.
I use rock salt or water softener salt, @ $5 for 50 lbs.
You could also use Nox-ick or some other product, they are just a more expensive way, and no better than salt.
You will need to keep salinity up fort least 2-3 weeks, to allow all dormant ick cysts to run thru their life cycle.
I have another thread, following advice from here. Changed the temperature to 86 from 80. Added about 2lb salt in 75 gallon aquarium (I assume it holds less than 75 gallons). Ordered some paraguard. I don't have gravel so not sure if vaccuming would help.