Qwertus

I couldn't find a fish illness section so I'll post here for now.

I have a small koi (about 5 inch) and 2 commets in a 55 gal temporarily. I recently add the koi and within a few days i notice the koi started to lose a few scales. Now the gold fishes start to lose scales too. The temperature is at 75 F atm and pH is around 6.5 from my most recent test today.

Normally to cure ich i just add aquarium salt and raise temp to 80 F, but with the gold fish and koi, is it going to be a problem for them?

Thanks for reading.