My Oscar Fish Seems to Have Cloudy Eyes
If poor water quality is not an issue then there are other things that may cause cloudy eyes in aquarium fish. Internal parasites such as flukes can also be the cause of cloudy eyes. You may not be aware that fish can develop cataracts. Unfortunately, there is no known treatment for cataracts in fish, I doubt whether it would be feasible for a veterinary surgeon to carry out an operation to remove cataracts. A bacterial infection within the I can also be the cause of cloudiness, in this case, a good quality antibiotic may help.
Fish need to the fed a healthy diet, an unhealthy diet may result in the fish suffering from a lack of vitamin A which again can affect the fish's eyes.
Finally, a fishes eye is extremely delicate so any damage caused by the fish either being attacked by another fish, or swimming into something in the tank could cause the eye to cloud over.
If you do notice that your fish start developing cloudy eyes then you must act quickly. Carry out increased water changes and if the cloudy eyes clear up quickly then it may have been down to your pH level. If increased water changes do not work then you will have to look at other forms of treatment.