Physicochemical Proprieties of Pond Water in the Economic Stimulus Programme (ESP) Fish Ponds in Tharaka-Nithi County, Kenya

Abstract

In an effort to attain food security, Kenya has embraced aquaculture as one of its strategies. From 2009, the Government established thousands of fish ponds through the Economic Stimulus Programme (ESP). TharakaNithi County was one of the places covered by the ESP and has 95% of its total ponds under the programme, stocked with the Nile tilapia (Oreochromis niloticus). Physicochemical properties of water influence overall pond productivity and fish yields. The ponds in Tharaka-Nithi County have suffered low production, the average production remaining at <30% of potential, with reports of stunting and frequent fish mortalities. This study aimed to investigate the physicochemical properties of the pond water in the county. Using the randomized complete block design (RCBD), the study area was divided into three zones whereby 27 fish ponds were studied. Chemical analysis was done according to the APHA Standard Methods and data analyzed using the one-way ANOVA. The Statistical Package for the Social Sciences (SPSS) Version 22.0 was used for correlations and regression analyses. Significant differences (p ˂ 0.05) were found in water temperature, dissolved oxygen, transparency, pH and conductivity among ponds in the three zones. Water temperatures, ammonia and PO4-P concentrations were outside the recommended range for optimum O. niloticus growth. Occasionally, DO and pH were outside those suitable for optimum tilapia growth, which could explain the frequent fish deaths and low aquaculture production. Regular monitoring of physicochemical parameters is recommended. These findings will be used by relevant government agencies and fish farmers to enhance fish production.