Green’s Dictionary of Slang

duck n.3

also Bombay duck
[the Bombay duck, the bummalo (Harpodon nehereus), a small local fish, usu. eaten dried as a relish]

(Anglo-Ind.) a nickname for residents of the Bombay Presidency.

[UK]M. Elphinstone in Colebrooke Life of the Honourable Mountstuart Elphinstone (1884) I 53: They have neither the comforts of a Bengal army, nor do they rough it like the Ducks. [footnote: A cant expression applied to the Bombay service.].
[UK]Lit. Chron. & Wkly Rev. (London) 22 May 335/2: All new comers in India are called Griffins, and they must be a twelvemonth and a day in the country, before they are considered free from the title, when they become Quie hies, Bombay Ducks, or whatever the term may be in the part of India they are situated.
[Ind]‘Sir Toby Rendrag’ Poems 26: [T]he European residents at Madras [have] the name of Mulls, from their liking of Mulligatawny soup; and at Bombay ‘Ducks,’ from the fish nick-named ‘Bombay Duck’.
[UK]New Sporting Mag. (London) Dec. 394: ‘Duck’ A species of the foregoing animal, but indigenous to Bombay, in general very harmless, receving its title from a fish of that name, to be found in Bombay and constituting the principal food of the said animals.
[UK]Allen’s Indian Mail 29 June 406/2: Now came the Madras civilians with a fearful grievance, that all the loaves and fishes of the north are gobbled by the Qui Hies – the troubled waters of the five rivers afford nothing to the benighted. The poor ducks again are once more left to suffer in silence.
[UK]N&Q Ser. 1 V 165: Residents of Bengal, Bombay, and Madras are, in Eastern parlance, designated ‘Qui Hies,’ ‘Ducks,’ and ‘Mulls.’.
[UK]C.W. ‘The Tiger-Slayers’ in Sporting Rev. Mar. 207: British officers of all grades and presidencies, whether Quihis, Mulls, or Ducks, can most thoroughly appreciate what is good in the eating line.
[Aus]Bell’s Life in Victoria (Melbourne) 25 Aug. 4/1: The ‘Bombay ducks’ consider their racing season to extend, through January, February, and part of March.
[Ind]F.E.W. Sketches of Native Life and Character in Southern India I 77: Proceeding to Bombay, he acted as butler and confidential servant to certain confiding ‘ducks’ until he had saved enough money again to set up as a ‘dubash’.
[Ind]R.F. Burton Sind Revisited I 68: Ducks, Bombayites – from the bummalow or bobil, the dried fish still called ‘Bombay Duck.
[UK]Jrnl East India Assoc. XV 414: We have, in Indian slang, the Calcutta ditchers, the Bombay ducks, and the Madras mulls.
[Ind]Yule & Burnell Hobson-Jobson (1996) 329: ducks, s. The slang distinctive name for gentlemen belonging to the Bombay service.
[Ind]G.K. Betham Lolapur Week 284: Madrasis are called ‘benighted ones’; while people hailing from Bombay rejoice in the appellation of ‘Bombay Ducks’.
[Ind]D. Dewar Bombay Ducks v: [T]he European residents of the Western Presidency were known as Bombay Ducks to distinguish them from Bengal Qui-his and Madras Mulls.