Water Quality and Growth Performance of Nile Tilapia (Oreochromis niloticus), Chia (Salvia hispanica) and Lemon Grass (Cymbopogon citratus) in a Media-based Aquaponics System

Abstract

High ammonia levels in enclosed fish production systems negatively impact fish growth and hinder optimum production. The objective of this study was to evaluate the (i) biofiltration potential of chia (Salvia hispanica) and lemon grass (Cymbopogon citratus) (ii) the influence of the plant filters on water quality and fish growth in an aquaponic system. Treatments included a control-without plants, S. hispanica, and C. citratus aquaponic systems. The study was conducted for 3 months in Aqualife fish farm, Machakos, Kenya. Water quality parameters, growth performance of fish and plants were monitored during the experiment. The plant treatments significantly (P< 0.05) reduced ammonia levels compared to the control (0.07 ± 0.17 mgL-1). There was a remarkable 32-fold decrease in ammonia compared to the hydroponic inlet. Planted aquaponic systems significantly (P < 0.05) reduced nitrite and nitrate concentrations compared to the control, indicating effective nutrient cycling and improved water quality. Notably, both S. hispanica (115. 5 ± 3.2 g) and C. citratus (130.3 ± 3.32 g) systems significantly (P < 0.05) boosted the growth performance of O. niloticus compared to the control (113. 5 ± 3.2 g). C. citratus performed better (450 ± 9.17 g) than S. hispanica (217.6 ± 2.52 g). These findings highlight the potential of the plants as sustainable and efficient biofilters, enhancing overall aquaponic system performance and contributing to a more productive and environmentally friendly approach to food production.