I have good luck with Ruby Reef "Kick Ich". I use it specifically for the fact it is invert and scaleless fish safe. My loaches and BGK do not mind it vs copper based treatments. It is a two week treatment and is pricey, but it works.
In my fw tanks I do 2 teaspoons of salt per gallon of water and rise temp to 84 degrees and it usually does the trick in saltwater I use coppersafe in fish only systems.
I have catfish and some ick medications are bad for them and usually you have to do 1/2 dose. One medication I found that worked well as Ich Attack, its organic and worked well with no side effects.