Gave my tank a big cleanout this morning and noticed that Boris, my Phaelena goby, was swimming around the top of the tank and didn't seem at all bothered with me messing around in the tank. He is normally a bit on the shy side if anyone is close to the tank.

On closer inspection I found that he couldn't see. Didn't respond to me sticking a hand alongside his head on either side so he obviously couldn't see it. Was able to touch him without him reacting much, although he did try to chew my finger. Watched him a bit longer and he was bumping into the glass and then I found him stuck on the overflow grate.

This is not the first time I have had a fish go blind on me. :oops: Have had a couple of clowns and chromis go blind too. Apart from not being able to see they appear perfectly healthy, no obvious physical problems, not skinny (although that soon changes once they can't see to eat), no spot or anything else.

I do have a couple of softies that are reputed to be a bit on the toxic side (devils hand, ricordea and a big rhodactis) but have had fish in the tank way longer than the goby and they don't seem to have any problems. I have a citron goby that sits in the devils hand all day.

Did a full spectrum water parameter check - all OK. I am at a loss as too why these fish have gone blind. Has anyone else out there had similar problems, more to the point have they figured out why. Has anyone got any suggestions as to why or what could be causing it? Any advice would be appreciated

Even if the fish was blind he'd react to your hand moving in the water near him. Most fish use their lateral line to sense movement in the water more than their eyes and they can navigate pretty well without eyes because they can usually feel the pressure waves from their own movement bouncing off glass, rocks, etc.

If he wasn't reacting at all it's because he's too far gone to care. Swimming dead, basically, not blind.

Yeah good point Ira.

He was reacting to the presence of the other fish around him. Still doesn't explain why an apparently perfectly healthy looking fish would suddenly not be able to see.

With the others when they appear to have gone blind, they obviously become an easy target and get very reclusive, hiding in holes, etc so nothing else can attack them. Since they can't see they dont come out and basically starve to death.

Any ideas as to what may cause them to go blind?