Effects of dietary taurine on tissue taurine and free amino acid levels of the chum salmon, Oncorhynchus keta, reared in freshwater and seawater environments.

1. Young chum salmon were fed on the basal and taurine-supplemented diets for 30 days in freshwater (FW) and for 25 days in seawater (SW). Levels of taurine, major free amino acids (FAA) and non-protein nitrogen (NPN) in various tissues were determined. 2. Tissue taurine levels were higher when fish were fed on the taurine-supplemented diets. All tissues of the SW fish did not contain higher taurine levels than those of the FW. 3. Levels of major FAA in the tissues differed little between fish fed on the basal and taurine-supplemented diets and also between the FW and SW fish. 4. No difference was observed in tissue NPN levels between fish ingesting the basal and taurine-supplemented diets; the levels were slightly higher in the SW fish.