He has been sitting on the bottom of the tank and not eating for a 3-4 days, this is the first time ive seen these whitish spots. Is this ich? Should i use medication? I have other fish in this tank, and no available quarantine tank. The only thing i have on-hand is aquarium salt. My nitrates have been very high recently, and im doing daily water changes of 25%-35%. What should i do? Help pls!!!