Just looked closer at the fishie..he is cute and looks happy but you said you clean the bowl every couple of days. Near the top of the bowl you can see where the water has evaporated. It looks like sometimes he goes longer than a couple of days without a water change. Granted a water change every couple of days can stress out any fish but it would be necessary in a bowl that small. Goldfish are big poopers! The water can become very toxic to them quite rapidly in a small home.
I bet he would be beautiful in a 10 gallon tank. Just think how active he would be then, not to mention happier!