Influence of Water Quality on Growth Dynamics of Nile Tilapia (Oreochromis niloticus) in Uasin Gishu Aquaculture Systems

Abstract

Aquaculture in Uasin Gishu County, Kenya, supports food security and livelihoods but faces challenges from unstable water quality affecting Nile tilapia (Oreochromis niloticus) growth. This study examined the relationship between water quality and fish growth across five farms representing earthen, tank, and raised liner systems from May 2023 to April 2024. Physico-chemical parameters—dissolved oxygen (DO), temperature, pH, chemical oxygen demand (COD), and biological oxygen demand (BOD)—were measured at three-hour intervals, while fish growth was monitored monthly. Data were analyzed using ANOVA, Tukey’s HSD, and multiple regression to assess water quality effects on growth. Temperature (21–23 °C) was below the optimal 25–30 °C range; pH (8–9) was acceptable; DO occasionally dropped below 3 mg/L; and COD (32–95 mg/L) and BOD (33–103 mg/L) indicated organic loading. Significant differences occurred among farms for temperature, DO, COD, and BOD. Growth parameters derived from the von Bertalanffy Growth Function showed the best performance in raised liner systems, with Cheplaskei Farm A recording the highest growth (L∞ = 36.78 cm; W∞ = 630.02 g). COD and BOD were the strongest predictors of maximum growth rate. The findings emphasize the need for stable water quality management to enhance O. niloticus productivity and ensure sustainable aquaculture in the region.