Ich is a very common parasite in fish. My favorite treatment is to use formalin malachite green. It is sold as Kordon rid ich plus. Any ich treatment works better in warmer water. Ich is almost untreatable in colder temperatures. Add 5 ml per 10 gallons of water. That is about 1 teaspoon of it. You can also use salt and warmer water, but this treatment is my favorite. Kordon rid ich plus is also good at treating fungus.