Plankton dynamics and physico-chemical parameters: A longitudinal investigation in carp and catfish culture ponds

An experiment was aimed to discover the overall scenario of physico-chemical parameters along with the qualitative and quantitative analysis of plankton in two different fish culture systems as carp mixed culture and catfish (Pangus) monoculture from September 2021 to February 2022 using conventional techniques. The mean values of transparency and dissolved oxygen (DO) noted at the catfish culture pond were lower than those at the mixed carp culture pond while pH mean values were observed to be higher in the catfish culture pond than in the mixed carp culture pond. A total of 21 genera of phytoplankton were found in both ponds under the groups of euglenophyceae (4), cyanophyceae (4), bacillariophyceae (5) and chlorophyceae (8). Among zooplankton, 13 genera were identified including Rotifera (7), copepoda (2), cladocera (3) and crustacean larvae (1) were recorded in mixed culture ponds whereas in catfish culture ponds, 11 zooplankton genera were recorded including Rotifera (5), copepoda (2), cladocera (3) and crustacean larvae (1). Planktonic abundances were statistically significantly different between the different levels (phytoplankton abundance in CCP, phytoplankton abundance in MCP, zooplankton abundance in CCP, zooplankton abundance in MCP), χ2(3) = 220.46, p < 0.001. Mixed culture pond cyanophyceae, bacillariophyceae, and euglenophyceae are positively associated with water temperature and pH but negatively correlated with DO. Rotifera is negatively associated with catfish culture pond water temperature, whereas chlorophyceae and cyanophyceae are favorably. Catfish monoculture ponds had higher phytoplankton abundance, so phytoplankton grazing fish species could be included with pangus culture to maintain a better water quality.