Do fish go Blind ?

[h2o]

I am having a bad week with my reef tank
1st I have algea hair out burst.
2nd my big percula disappeared (presumed dead) and couldn't find it.
Now I fed my tank with brine shrimp and my Cardinal seems blind, brine shrimps passed by him and he wouldn't touch it, as if he couldn't see anything. Other fish ate well. I then spent time trying to verify if it's blind, it was still able to react when he saw my hands moving in front of him. I have had him almost 2 years. what's wrong?
tested water 2nd consecutive day, nitrate is up 6ppm, ph 8.2, phosphate still 0, calcium still 550, i have 3 powerhead on all time now, cuz i couldn't find a dead percula. Cleaning crew will arrive tomorrow. What the hell is wrong with my tank??????????
<img src="graemlins//confused.gif" border="0" alt="[confused]" /> <img src="graemlins//confused.gif" border="0" alt="[confused]" /> <img src="graemlins//confused.gif" border="0" alt="[confused]" />

 

[stupid_naso]

You know what? I had the same experience, but instead of cardinal, I have a naso tang. Food was right in front of him and he turns away. He died about couple of days later. So, can they be blind? No idea.

 

[pinkerton]

You should test your water quality and figure out if your clown died from poor water conditions. If he didn't die from that you might safely be able to induce that it was fungal/bacterial, in which case perhaps your cardinal is coming down with the same thing. Which could explain why he is not eating. {i know its kind of a stretch} but I am doubting your fish went blind unless, you noticed severe cloudiness and/or pop eye? Hope that helps in some form.
-Laura