sea donkey

noun3

1. •
   The common name for various fish, especially the hake or the spadefish.

   • The ectoparasitic isopod, Nerocila armata Dana, so common on the head of small Sea Donkey (Chaetodipterus faber) was also sometimes attached to Sea Trout fins or head. — 1958
2. •
   A term of opprobrium.

   • You've more brass than a highwayman, you fat-headed sea-donkey! — 1876
3. •
   Someone or something that lives or works at sea and is similar in some way to a donkey, especially by performing humble tasks.

   • Looking at me you would think that I am just an old 'sea donkey'; you would never have thought that I have shaken hands with the very Emperor of Great Britain! — 1947