Water quality is the most important limiting factor in fish production and directly affects feed efficiency, growth rate, fish’s health, survival and disease progression. The aims of this study were to evaluate the physico chemical parameters and microbial loads o f water samples collected from different pond types, water sources, geographical locations , and aquaculture systems . A cross-sectional study was done in 6 ponds from 6 farms in Nakuru and 4 ponds from 1 farm in Narok counties in the month of July 2023. Water parameters including dissolved oxygen (DO) , pH, phosphorous (P) , electrical conductivity (EC), turbidity, total suspended solid (TSS) , ammonia , and nitrate were measured onsite and ex situ following standard methods (Figure 1.) Microbial quantification for the10 water samples was done using the Miles-Misra technique.
The pH ranged between 8.12 to 9.76 in concrete ponds, and 9.28 to 10.41 in liner ponds and was 7.47 in plastic tank ponds . Temperatures ranged from 21oC to 27o C in liner ponds and 27oC to 28oC in concrete ponds . The temperature in plastic tank ponds was 22oC. Total aerobic bacterial counts ranged betwee n 80 to 360 cfu/ml in concrete water tanks and 80 to 3200 cfu/ml in liner ponds . Open system liner ponds showed great variability in bacterial counts hence high variance on overall viable bacterial counts (Figure 1.) The aerobic bacterial count was 40 cfu/ml in the plastic tank pond . The physic ochemical parameters and microbial loads were generally higher in open aquaculture system, borehole water and liner ponds and less in closed aquaculture system, river water and tanks . Aquaculture practices influence the overall water characteristics, and aerobic microbial load. Aquaculture practices like closed aquaculture system should therefore be adopted to aid in optimising water quality parameters for fish production.
Key words: Water quality, Aerobic microbial load; Physic ochemical; Aquaculture systems