The epidermal mucus of fish contains antimicrobial agents that act as biological defence against disease. This study aims to identify antibacterial activity and protein concentration of epidermal mucus of Barbodes everetti, a Bornean endemic freshwater fish. The epidermal mucus was extracted with 3% acetic acid, 0.85% sodium chloride and crude solvents. The mucus activity against eight strains of human pathogenic bacteria, including Bacillus cereus ATCC 33019, Escherichia coli O157:H7, Listeria monocytogenes ATCC 7644, Pseudomonas aeruginosa ATCC 27853, Salmonella braenderup ATCC BAA 664, Salmonella typhimurium, Staphylococcus aureus ATCC 25933, and Vibrio cholerae, were tested. The acetic acid mucus extract of B. everetti was able to inhibit five strains of bacteria and show no activity toward E. coli O157:H7, B. cereus ATCC 33019 and L. monocytogenes ATCC 7644. Moreover, the highest protein concentration was quantified in crude extract, followed by aqueous and acetic acid extracts. This study provides a preliminary knowledge on the activity of epidermal mucus of B. everetti towards five out of the eight human pathogens tested, therefore it may contain potential sources of novel antibacterial components which could be further extracted for the production of natural antibiotics towards human-related pathogenic bacteria.
The fish health status and parasitic infection in paddy fields are understudied in Borneo. This study was done to compare the prevalence and abundance of parasites on freshwater fishes in the upstream and downstream rivers of paddy fields. Parasite study on freshwater fishes was done by collecting live fish samples using ten minnow traps with baits at each site in Serian and Padawan, Sarawak, from October 2017 until March 2018. A total of 120 freshwater fishes were examined during this study period. Cold anaesthesia was applied on live samples prior to ectoparasite and endoparasite microscopic screening, which involved scraping of outer body mucous and removal of fish intestines, respectively. No ectoparasites were recovered from the fish samples. A total of 19 (15.83%) fishes from Cyprinids were infected with endoparasites. From these, 58 individuals of endoparasites were recovered. Two groups of parasites, namely Nematoda (Cucullanus sp.) and Trematoda (unidentified), were recovered from the fish intestines. From this study, there was a significant difference between the upstream fishes and downstream fishes in their endoparasite infection at both Triboh Village (p = 0.035) and Annah Rais Village (p = 1.445 × 10-6) using two samples t-test. The endoparasite abundance in fish was higher in the streams where there was less human disturbance. This study may serve as a baseline study on the parasitic infections of freshwater fishes in streams near paddy fields or other agricultural area in Sarawak.