Can fish go blind?

[Bartman]

I previously posted trying to figure out why my clowns have stopped eating. It has been 2 months so they must be eating something or I'm sure they would have starved by now. They just don't come out of their host when I put food in but I have noticed that the larger clown appears to be looking for food when it comes by but just can't find it. She'll follow food that brushes against her but never seems to get it. The smaller clown never leaves their host (colt) if the larger doesn't. So, I'm wondering if it's possible that the larger clown can't see the food anymore?