Green’s Dictionary of Slang

1. (Aus./US) any form of canned fish.

1906		C. M’Govern ‘Soldier Sl.’ in Sarjint Larry an’ Frinds n.p.: gold-fish: — Canned Salmon.
1907		C. M’Govern By Bolo and Krag 42: I remembered how the soldiers in the 39th ust to turn up their noses when canned salmon was the menu for supper, and make all sorts of derisive remarks about ‘two-eyed beefsteak’ and ‘redmoike’ and ‘gold-fish’.
1918		letter in M. Baldwin Canteening Overseas (1920) 149: After a delicious lunch of bully beef and gold fish (salmon) we prepared to return.
1926		(con. 1918) L. Nason Chevrons 27: He issued out a can o’ goldfish.
1936		Mencken Amer. Lang. (4th edn) 573: The greater part of the American vocabulary came from the Regular Army, and some of it was of very respectable antiquity, e.g. [...] gold-fish (canned salmon), gob, leatherneck, padre, chow and punk (bread).
1946		J.W. Bishop ‘American Army Speech’ in AS XXI:4 Dec. 244: Even the odious C and K rations are either given their full titles or referred to as C’s and K’s. I heard little approximating the goldfish and monkeymeat of the last war.
1952		T.A.G. Hungerford Ridge and River (1966) 189: It’s no wonder he can walk the way he does, the tough old bastard [...] We would, too, on flaming pigeon-pie every day instead of bullamacow and goldfish!

2. (US black) sliced, canned peaches.

1940		‘C.C.C. Chatter’ in AS XV:2 Apr. 211/2: Common articles of food lose some of their sameness when given figurative names: [...] sliced peaches, gold fish.
1947		M.H. Boulware Jive and Sl.
1972		B. Rodgers Queens’ Vernacular 98: gold fish (rare, lunch-counter sl) sliced peaches.