FISH ONLY fish with fins and scales are kosher. Fresh fish must be recognisable as being of a kosher species. Jewish law therefore forbids the use of fillets which do not have the scaled skin attached and are not recognisable as being from a kosher species unless a Rabbinic supervisor is present or the customer supervises the filleting of such fish. The supervisor should ensure that the knives and boards used are thoroughly clean before cutting commences. Should there be any doubt as to whether the fillets or cutlets have been cut with a clean knife, then the fish must be thoroughly washed in cold water before use. It is forbidden to purchase minced fish which has not been minced under the supervision of a Rabbinic supervisor.