What is "onion fish"

Grenadier \Gren`a*dier"\, n. [F. grenadier. See Grenade.]

1. (Mil.) Originaly, a soldier who carried and threw grenades; afterward, one of a company attached to each regiment or battalion, taking post on the right of the line, and wearing a peculiar uniform. In modern times, a member of a special regiment or corps; as, a grenadier of the guard of Napoleon I. one of the regiment of Grenadier Guards of the British army, etc.

   Note: The feats of grenadiers have been memorialized in song, as in the following: (for the melody see http://www.acronet.net/~robokopp/english.html) Some talk of Alexander, and some of Hercules / The British Grenadiers ca. 18th Century The British Grenadiers Some talk of Alexander, And some of Hercules Of Hector and Lysander, And such great names as these. But of all the world's great heroes, There's none that can compare With a tow, row, row, row, row, row, To the British Grenadier.

2. Those heroes of antiquity Ne'er saw a cannon ball Or knew the force of powder To slay their foes withall. But our brave boys do know it, And banish all their fears, Sing tow, row, row, row, row, row, For the British Grenadier.

3. Whene'er we are commanded To storm the palisades Our leaders march with fusees, And we with hand grenades. We throw them from the glacis, About the enemies' ears. Sing tow, row, row, row, row, row, The British Grenadiers.

4. And when the siege is over, We to the town repair The townsmen cry, "Hurra, boys, Here comes a Grenadier!" Here come the Grenadiers, my boys, Who know no doubts or fears! Then sing tow, row, row, row, row, row, The British Grenadiers.

5. Then let us fill a bumper, And drink a health to those Who carry caps and pouches, And wear the louped clothes. May they and their commanders Live happy all their years With a tow, row, row, row, row, row, For the British Grenadiers.

   2. (Zo["o]l.) Any marine fish of the genus Macrurus, in which the body and tail taper to a point; they mostly inhabit the deep sea; -- called also onion fish, and rat-tail fish.

   3. (Zo["o]l.) A bright-colored South African grosbeak ( Pyromelana orix), having the back red and the lower parts black.

n. (context obsolete dialect English) A fish, the grenadier.