The Regulation applies to fishery products that are covered by 1603, 1604 and 1605 of the Customs Trade Tariff. Freshwater and farmed (aquaculture) fish are all out of scope of the Regulation as are marine fish imported for ornamental purposes.
Commission Regulation 202/2011 identifies some exclusions, this includes clams and other bivalve molluscs. Shrimps, prawns and squid all require a catch certificate along with scampi (unless freshwater).
There are no other exemptions to the Regulations for imports of samples (i.e. all imports need a certificate).
Composite Products
Products made up of fish and other ingredients may be covered by the Regulation. If the composition of the product contains is a fish content of over 50% then it will almost certainly come under the import rules. Where there is less than 50%, but fish is the main ingredient, then this will also require checks.