French to English Other Cooking / Culinary

Another term from the same magazine which is proving quite challenging! I'm confused by the start of this sentence which seems to imply that the fishmongers was initiated by a shoal of fish! Obviously I'm missing some subtle meaning here which is clearly not the literal one! Thanks.

Initiée par un banc de poissons l’année passée, la poissonnerie de la Brasserie Guillaume permet aux palais les plus exigeants, et ce depuis quelques semaines, d’acheter poissons et fruits de mer frais.