Utilization of Inland saline underground water for bio-integration of Nile tilapia (Oreochromis niloticus) and spinach (Spinacia oleracea)

Abstract An experimental trial of 45 days was conducted with different Nile tilapia ( Oreochromis niloticus ) to spinach ( Spinacia oleracea) ratios in a recirculating aquaponics system using inland saline groundwater of salinity 3 g l −1 . Different fish to plant ratios, T1 (1:0.7), T2 (1:1), T3 (1:1.3) and C1 (aquaponics without plants), C2 (without hydroponic component) were assigned as treatments and control groups respectively. Total yield of O. niloticus (4.69 ± 0.04 Kg m -3 ), spinach yield (1.42 ± 0.02 Kg/bed) and percentage removal of nitrate (50.43 ± 0.11%), phosphate (47.62 ± 2.20%), and potassium (54.26 ± 1.23%) from the effluent was found to be higher in T3. The daily water requirement of T1, T2, T3 and C1 (1.16–1.29%) was significantly lower compared to C2 (17.67%). Findings of the experiment suggest that aquaponics is feasible with low saline underground water and a ratio of 1:1.3 (Nile tilapia: spinach) is the best among tested ratios for balancing nutrient generation and removal as well as fish and plant production. However, further studies using higher fish to plant ratio could be carried out for optimisation of such systems.