They caught a fish with xanthurism. What is this disorder?

On October 14, researchers discovered a common ling with a rare coloration due to xanthochromism during routine monitoring in Oswego Harbor, New York. This was the first documented catch of this species in the area, although its population in Lake Ontario is extremely low. The fish exhibited yellow-orange skin, a result of a genetic mutation. Upon examination, scientists noted the fish was underweight and sent it to Cornell University for health analysis, which could provide insights into the common ling population and conservation efforts.