The eyes have it

Eye whites give off signals about health and social status of salmon

source: New Scientist September 22 2001 p25

The eye whites of salmon give off signals about the health and social status of the fish, according to Glasgow University’s Hayley Suter and team from the unit for fish biology. The sclera, or white of salomn’s eyes, is a light cream colour in dominant fish, becoming darker when the fish are ill. Dark sclera are found in fish of low status, and their eye whites become lighter if they are victorious in a battle, or eat a meal. A meal of a few worms can lighten the colour of a low-status fish’s eye white.