Abstract: The invention concerns a method for the preparation of fish mass wherein the fish meat is separated from fat, pigment and entrail remains. The method can be utilized for fatty as well as for lean fish. This is achieved by holding fatty or lean fish raw material in an aqueous environment in which the pH is adjusted to pH 3-5, preferably pH 4, and in which the temperature is adjusted within the range of 20.degree.-50.degree. C. The fish meat with fish bones is separated from the liquid aqueous solution containing fat, entrail remains, and dissolved skin and abdominal epithelium and dark pigments from these, by methods known per se. The resulting fish mass is well suited for use as raw material in the production of manufactured foods, as the fish muscle proteins are not substantially denatured by the process.