Fishwife
A fishwife, fish-fag or fishlass is a woman who sells fish. In this context, the word wife means woman rather than married woman. This usage stems from Old English wif (woman) and is similar to the German Weib, also meaning "woman" (nowadays rarely used and usually in a pejorative sense).
Often the wives and daughters of fishermen, fishwives were notoriously loud and foul-mouthed, as noted in the expression, To swear like a fishwife. One reason for their outspokenness is that their wares were highly perishable and so lost value if not sold quickly.
Fishwives in fishing villages such as Cullercoats and Newhaven were noted for their beauty, hardiness and industry and were celebrated by artists and royalty.
Billingsgate
London's traditional fish market was frequented by such types who were known as "the wives of Billingsgate". "They dressed in strong 'stuff' gowns and quilted petticoats; their hair, caps and bonnets were flattened into one indistinguishable mass upon their heads. ... They smoked small pipes of tobacco, took snuff, drank gin and were known for their colourful language."