Green’s Dictionary of Slang

1. a corpse.

1960, 1975

(ref. to 1929) Wentworth & Flexner DAS 131/2: croppy n. A corpse. 1929: ‘That kid need a doctor [...] If you don’t want a croppy on your hands’ G. Jones. Railroad use.

2. a dead fish.

1920

S. Lewis Main Street (1921) 18: A fisherman in shirt sleeves and a wide straw hat, holding up a string of croppies.