The plant, opened by retailer Waitrose last week, will process up to 100 metric tons of plaice and lemon sole from Iceland per day.
Processor Flatfish marked its 30th birthday at the event with the opening of the new plant following completion of its latest £2 million (€2.2 million/$3.2 million) extension.
Guests were present from NatWest, Grimsby Fish Merchants' Association, Waitrose and Atlantic Fresh, among others.
