Blood serum lysozyme in some aquaculture objects (orders Cypriniformes and Perciformes) from Central Vietnam

Determination of serum lysozyme in seven fish species of the orders Cypriniformes and Perci-formes, grown in the tropics, is carried out. The absence of enzyme activity in carps is detected. From low to middle levels of lysozyme in Perciformes are recorded. Comparison between carps from the tropics and temperate latitudes shows low serum lysozyme activity or its absence regardless of habitat. Perch-like species demonstrate low and middle levels of lysozyme both in the tropics and temperate latitudes. It is suggested, fish species maintain a physiologically optimal level of lysozyme in the blood in the successful adaptation to the conditions that differ significantly in the temperature regime. Probably the immunomodulatory action of increased temperature has an effect limited by force and time on the lysozyme level.