English: Arms of the Worshipful Company of Fishmongers: Azure, three dolphins embowed in pale between two pairs of sea luces saltirewise proper crowned or on a chief gules six keys in three saltires ward ends upwards of the second. Note: sea luces are hake, Merluccius Bilinearis (mer luccius = sea lucy (sea pike)). The crossed keys are the emblem of St Peter.

From: Heraldry of Fish: Notices of the Principal Families Bearing Fish in Their Arms By Thomas Moule, pp.171-2:

King Henry VI. united the Stockfishmongers and other branches of the trade, and incorporated the whole under the general name of the Fishmongers of London,t but they were again separated in the reign of Henry VII. The arms of the Saltfishmongers were gules, three crossed keys saltierwise or, on a chief azure three dolphins embowed argent. The Stockfishmongers bore for arms, azure, two sea luces in saltier, proper, with coronets over their mouths or : the fish here intended is the hake, the merlucius of the naturalist, common on the southern coast of England, large quantities of which are preserved, both by salting and drying, for exportation, chiefly to Spain. The two companies of Salt and Stockfishmongers, both under the patronage of Saint Peter, were united in 1536, when they obtained a charter from King Henry VIII; The insignia now borne, an amalgamation of the two arms formerly used, were confirmed to the company by Robert Cooke, Clarenceux King of Arms in 1575; * the grant of arms was again confirmed in the year 1634. (Source: Heraldry of Fish: Notices of the Principal Families Bearing Fish in Their Arms By Thomas Moule, pp.171-2 [1]