Why does my goldfish have white fuzzy growth on its head?

White fuzzy material on a goldfish’s head is very likely a case of Ich, or white spot disease. Besides the white fuzz, a goldfish with Ich usually shows poor spirits, reduced appetite, and little activity, so watch for these signs.

Goldfish Ich is mainly caused by large swings in water temperature. In this case, add a suitable amount of malachite green to the water each day, and the goldfish should improve within about a week.

During this period, keep the water temperature steady to prevent the goldfish from falling ill again.