Abstract
Fish culture is dependent upon ecological parameters such as light, temperature, dissolved oxygen, pH and total alkalinity. The pH of soil in Pakistan is alkaline which subsequently influences the pH of the water used for fish farming. Present study was designed to determine the effects of alkaline pH on the composition of fish epidermal mucus. Mucus was extracted from anaesthetized and alkali treated groups of Labeo rohita. Total volume of mucus collected from anaesthesia treated group was 150 +/- 11.78ml and 480 +/- 24.25ml from alkali treated group. Difference was observed in the mucus appearance, viscosity and odor. HPLC analysis of mucus obtained from anesthetized group showed nine peaks at 280nm and 360nm whereas the mucus collected from alkali treated group depicted only two peaks at 280nm and five peaks at 360nm. Four units of lectin activity were observed in the mucus from the anesthetized group but were altogether absent in the mucus from the alkali treated group. Fatty acid profile by GCMS depicted the presence of acetic acid and 68 carbon chain fatty acids in the mucus extracted from both anesthetized and alkali treated groups. These results indicated that higher pH has denatured or deteriorated proteins in the epidermal mucus of fish and caused lectin activity to cease completely, however alkaline pH has no adverse effect on fish mucosal fatty acids. Further studies are needed to evaluate the effects of higher pH on fish immune parameters such as non-specific immunity, microbial resistance and disease susceptibility.