Yellowtail \Yel"low*tail`\, n. (Zo["o]l.)
   (a) Any one of several species of marine carangoid fishes of the genus Seriola; especially, the large California species (S. dorsalis) which sometimes weighs thirty or forty pounds, and is highly esteemed as a food fish; -- called also cavasina, and white salmon.
   (b) The mademoiselle, or silver perch.
   (c) The menhaden.
   (d) The runner, 12.
   (e) A California rockfish (Sebastodes flavidus).
   (f) The sailor's choice (Diplodus rhomboides).

Note: Several other fishes are also locally called yellowtail.

Source: Webster's Revised Unabridged Dictionary (1913)