Epidermal mucus as a potential biological and biochemical matrix for fish health analysis

Fish reside in ecosystems teeming with pathogens, so their mucus has developed antimicrobial properties that help inhibit these pathogens. The fish's epidermal mucus serves as the initial line of defense against pathogens. This study aimed to characterize the antibacterial activity and biochemical makeup of fish skin mucus against various bacterial strains. The analysis was conducted on Labeo rohita, a fish species chosen for its mucus sample. The mucus was tested for its antibacterial activity against multiple Gram-positive and Gram-negative bacteria. The results showed that the crude mucus extract had higher activity than the saline mucus extract. The fish mucus's antimicrobial potential was assessed using the well diffusion method. The crude mucus extract displayed slightly better antibacterial activity against Gram-negative bacteria like Escherichia coli and Pasterulla multocida, as well as Gram-positive bacteria like Staphylococcus aureus and Bacillus subtilis, compared to the saline mucus extract of Labeo rohita. The samples were also tested for their hemolytic and thrombolytic activities. The activity of antioxidants in fish mucus was evaluated using DPPH, reducing power, TPC, and TFC assays. Additionally, biochemical analysis was performed, including measurements of CAT, POD, SOD, and protein content. Advanced techniques such as Fourier infrared spectroscopy (FTIR) and UV spectroscopy were employed for the characterization of fish mucus. FTIR analysis of fish mucus revealed the presence of aliphatic primary amines (N-H) and alkenes as functional groups at various peaks in the spectrum. The results were analyzed using mean and standard deviations.