And if anyone needs a third opinion, this link has the fish information on page 6;
http://www.ukba.homeoffice.gov.uk/si...nging-food.pdf
fish and fish products
You are allowed up to 20kg combined weight per person of fish and fish products (including dead bivalves) or the weight of one fish whichever weight is highest. Fish can be dried, cooked, cured, smoked or fresh but fresh fish is only allowed if it is gutted.
Of course, tryst doesn't guarantee the airline will accept it for transport, so make sure it's wrapped and packed nicely as mentioned up-thread.