Chemical composition of muscle tissue of fish reared in the aquaculture of South Vietnam

To study the chemical composition of four species of valuable fish reared in aquaculture conditions in South Vietnam.Individuals of Channa striata, Channa gachua, Oreochromis niloticus, a hybrid of Clarias gariepinus and Clarias macrocephalus were purchased in markets from farmers of cage farms and directly in the farms of Khanh Hoa province. The fish were measured, weighed, and then muscle tissue was dissected for chemical analysis. The water content in the tissue was determined by a two‐stage method for determining moisture, while lipids were determined by the fat‐free residue method in a Soxhlet apparatus. The amount of protein was obtained according to the principle of the Kjeldahl method, using a semi‐automatic distillation unit UDK 139 (Velp Scientifica, Italy, 2011); minerals were determined by the gravimetric method, and carbohydrates – by calculation. The index of physiological state was calculated according to the standard method.Hybrid catfish muscles are characterised as having the greatest nutritional value. In terms of lipid content, the individuals studied belonged to fish with a low fat content, Channa striata, which belongs to the category of lean fish. A high index of physiological state in Oreochromis niloticus was found to be associated with increased water content in muscle tissue. No significant differences were found between the biochemical parameters in the muscles of fish with an increase in body size, and only in Channa striata did the proportion of minerals increase. The data obtained can be used in the organisation of rational feeding and maintenance of aquacultural species.