Light-horn

The Light Horn is a mythical Britannian fish, which is mentioned briefly in Ultima VI.

Description
Light horns take their name from the glowing horns that are said to protrude from their heads. According to folklore, the light horns are very vain, and will swim near the surface of the water when the sea is glassy and still that they might admire the splendidness of their horns. It is under such conditions that these cryptids may supposedly be caught, and those who can succeed in such an endeavor are said to win good fortune for accomplishing such a feat.