lucy is right..
. as i seen the shape on ur fish,the fish hv an in blance feature and this fish should go for a lower water level forever and separated from the rest.
My suggestion is 5 inch high and feed more staple food than high protein food.pls, don't feed him food that contain wheat-germ as the fish is building fat not muscle .built fat is very bad for the fish specially the short body form.hope that help.cheers.