Cloudy Eye is a symptom not truly a disease in and of itself.
Cloudy eye is pretty well known and is usually due to poor water quality (high nitrate, ammonia or such)
or to a fungal infection. Cloudy eye is a condition in which the eye appears to be cover with an opaque film.
Cloudy eye is typically a secondary bacterial or fungal infection. Cloudy eye can also appear when the
pH drops too low, when the fish freaked out and panicked and ran into something and scratched its eye or
when fish fighting; Fish always go for another fishes eyes when they fight so it might have got damaged.
Photo by: Killer
Do 25% water change and check pH. Repeat water change in two days. If that doesn't do it you should
treat the cloudy eye with antibiotics such as Tetracycline.
Keep water chemistry in proper levels it is the key to prevent Cloudy Eye.