The tuna is found in some medieval encyclopedias. They arrive in the Spring. They see better with their right eye, so they approach on the right and leave on the left. They follow ships out of curiosity to see the sails driven by the wind; and they are so astonished by this that they are not afraid when tridents are thrown at them. They hibernate deep in the water in winter.

If the eyes or lungs of the tuna are dissolved in seawater, anything written with the liquid will shine like a flame.