Abstract: The present invention relates to a method of cooling and preservation of fish and fish products from thus treated fish. The fish is cooled by a cooling medium in tanks, containers or other suitable facilities, and also subjected to treatment of at least one preservative agent. The fish is subjected to a combined treatment of a cooling medium and a preservative agent and said treatment is performed by means of a cooling medium comprising C.sub.1-4 monocarboxylic acids and/or mono/di or tetra salts of alkali- and/or earth alkal salts of said acids. The cooling is performed by a cooling medium, being an aqueous solution of C.sub.1-4 monocarboxylic salts in a concentration of 5-30 weight % salts and 95-70% weight water, or binary ice comprising a preservative agent. The most preferred brine or binary ice comprises potassium formate and/or potassium diformate and/or formic acid. The pH of the brine can be adjusted by addition of an acid or disalt being the equivalent of the monosalt applied in the brine.