EFFECT OF ALKALINE PH ON FUNGAL RESISTANCE, TOTAL PROTEIN AND TOTAL LIPIDS OF CLARIAS GARIEPINUS SKIN MUCUS

Abstract

The effect of alkaline pH on fungal resistance, total protein and total lipids of Clarias gariepinus skin mucus was investigated in this study. C. gariepinus samples in renewal static bioassay were subjected to alkaline pH, alkaline + buffer solution, and skin mucus collected from the dorsal surface of fish for comparison with mucus from control fish. Antifungal activities of mucus from treatments and control fish were determined using sensitivity test. Total protein and total lipid contents of fish mucus were
analyzed using Kjeldahl method and Soxhlet extractor respectively. Zones of inhibition were used to determine the sensitivity of mucus from treatment and control fish against fungal isolates. Fungi isolated from fish culture medium were Apergillus flavus, Aspergillus niger, Mucor mucedo, Rhizopus stolonifer and Penicillium species. Pooled mucus of C. gariepinus from treatments and control exhibited antifungal activity against fungal isolates. Mucus of C. gariepinus from control had higher zones of inhibition compared to treatments. M. mucedo with 19.4 mm zone of inhibition was more sensitive (P>0.05) to antifungal activity of C. gariepinus. A. niger had significantly (P<0.05) lower zones of inhibition in alkaline pH. Total protein and total lipid were highest in alkaline pH mucus. C. gariepinus mucus was defensive against fungal pathogens of C. gariepinus. This study has shown that alkaline pH probably reduces the antifungal activity of C. gariepinus mucus and may elicit less resistance to fungal species. This study is probably novel in reporting the negative impact of alkaline pH on fungal resistance of C. gariepinus mucus. Monitoring pH levels especially in intensive aquaculture is important for fish health management