I bought 2 new male mollies and 2 new male guppies today and one of the guppies seems to have cloudy eye in one eye. I hadn't noticed this in the shop but I happened to top up on API Melafix and Primafix when I got the fish, I needed some anyway. Should I treat the whole tank with just Melafix or both Melafix & Primafix? The new fish are currently in quarantine so I can treat them without risk coming to my other fish.