Comparative Immunological and Biochemical Properties of the Epidermal Mucus from Three Brackishwater Fishes

Immunological and biochemical properties of skin mucus of different fish species may have mutual beneficial effects on health management when the fishes are farmed together in same system. Present experiment was conducted to investigate and compare the immunological and biochemical properties of epidermal mucus of three brackishwater fishes, namely Lates calcarifer, Chanos chanos and Mugil cephalus. Mucus was collected from the dorso-lateral surface of six individual fish of each species and used for analysis of immunological properties and biochemical composition. Innate immune parameters such as lysozyme, haemolytic, phagocytic activities and lectin were significantly (p < 0.05) more prominent in the mucus of C. chanos followed by that of L. calcarifer and M. cephalus. Similarly, mucus of C. chanos exhibited maximum protease, alkaline phosphatase, and antibacterial activities. UV spectral analysis showed the presence of toluene, isoquinoline, 2-furaldehyde, octadecenoic acid, biphenyl, thymidine, and cinnamic acid in the mucus of L. calcarifer, whereas these were absent in other two species. Fourier transform-infrared spectrum analysis revealed that isothiocyanate, aldehyde and alkene were common functional groups in the mucus of all three fishes. The results indicated that mucus of C. chanos has stronger innate immune properties as compared to that of other two fishes and therefore, polyculture of this fish with other fish or shrimp species may have beneficial effects for disease prevention.