Rainbow Shark with cataract ?

Hi all,
I have a rainbow shark (albino, pinkish white body with red tail and fins) that appears to be blind in one eye ? One eye seems fine, large red pupil, the other seems clouded over and bulges out a bit more than the other. I've had the little guy a couple of months but only just noticed this today. I just came back from 2 weeks holiday and had one of those vacation food things in the tank (the ones that slowly disolve and release food). I was wondering what may have caused this or if he may have injured himself while I was away, scraped against the gravel or something. Or maybe he's not eating properly or maybe something to do with the water ? I'm pretty new at this and would appreciate any advice from anyone who may have come across this sort of thing before. Except for the bung eye he all else seems healthy. Thanks.

 

Cloudy Eye- Cloudy eye can have many causes. Look for signs of Velvet Disease, Ick, and Fish tuberculosis. However, sometimes this is caused due to bacterial infections. Symptoms: One or both eyes become cloudy, and take a whitish appearance. Fish may show signs of distress, and be off-color and behave abnormally. Treatment: Establishing the likely cause of the problem and treating it as soon as possible is the best way to prevent damage to your fish's nervous system. The incidences of cloudy eye can be maintained by keeping the water quality in a good condition, and adding a small amount of aquarium salt to the water at water changes. There are many good medications available at your local pet stores that deal with this problem. Follow the recommended accordingly. this is from http://www.goldfishinfo.com/ailment1.htm#cloudy

I have found Melafix™ to work quite well.

I hope this helps, I am more into Saltwater but sometimes the diseases are similar...................... John