I've always thought he may be vision impaired in one eye. If he swims with his left eye towards the outside of the tank, he doesn't see my finger, but once he turns around to the other side, he follows my finger perfectly. And sometimes he sees his food, and sometimes he doesnt. Its like he has to swim around his food so he can see it in his good eye. His eyes are also two different colors; one is red and the other is black. I cant check to see if its cloudy because he moves around too much, and usually he only has his good eye facing towards me.