I had a large blind goldfish for years in my small pond... missing one eye.. and his other was white. They will get use to their surroundings and adjust. He would eventually come up to feed like the rest... though a bit more haphazardly.

Now specifically to your fish... carnival fish typically aren't kept in the best of conditions.. so there is a decent chance he/she has other issues going on that is causing the lethargy and disinterest in food. It is at least a good sign that it’s pecking at the algae sides… but it should react to food in the water. Try crumbling up the food a bit to “chum” the water by it. Or for floating pellets you can squeeze the air from them under the water and let it sink down to the fish to see what happens.

Thank you very much for your response. My little pond started for water lilies some time ago and feeder fish were added for mosquito control. My current "feeder" fish were added to the pond about 2 years ago. They are all healthy and active.

The "carnival" fish were won 5 years ago and kept in a 10 gallon tank for 5 years! I adopted them 4 months ago. They are twice the size of my little fish. Spot was almost round due to generous feeding and a tank to small to have a good swim in. When I would run my wave maker he would bob like a school bus in a flood. He has since trimmed down and become quite a fast swimmer though he still is quite the piggy at feeding time.

Scott who I believe is blind is smaller that Spot but still large. He is active and has no issues interacting with the other fish. On close inspection one of his eyes is cloudy and the other has a blister/bubble over it.

I have started a routine at feeding time. I turn off the pump/fountain before I feed and then only drop a few pellets at a time. Scott is seeming to get the connection as he swims faster and comes to the top more at this time. He mostly roots near the side so when he does this I drop a couple pellets where he is rooting. He has gotten a couple and seems quite pleased with himself when he does. He does get a little over excited when he hears the other fish splashing while eating but I think with practice he will calm and I can keep him fed.