No abstract

This study was carried out to find suitable salinity for the best growth performance and survival of Nile tilapia (Oreochromis niloticus) with spinach (Spinacia oleracea) in an aquaponic system. The experimental design consisted of inland saline groundwater with salinities 3, 6 and 9 g L−1 as treatments and freshwater as control, carried out in 12 identical aquaponics units with fish stocked at a biomass 1.3 kg m−3 and plants at a density 40 m−2. Nile tilapia reared at salinities 9, 6 and 3 g L−1 showed significantly higher (p < 0.05) feed efficiency ratio and protein efficiency ratio compared to freshwater. The feed conversion ratio of fish at salinities 9, 6 and 3 g L−1 ranged between 1.31–1.43 and significantly differed from control. Final mean biomass were statistically similar at 9 g L−1 (5 kg m−3), 6 g L−1 (4.92 kg m−3) and 3 g L−1 (4.68 kg m−3). Survival of O. niloticus was 100% in all the salinities tested. Spinach was harvested twice during the study, in the first harvest the yield was observed higher in freshwater followed by 3, 6 and 9 g L−1, but in the second harvest, the higher yield was observed in 9 g L−1 followed by 6 g L−1, 3 g L−1 and freshwater. Based on the overall production performance and water quality parameters, a salinity of 9 g L−1 was found to be the best for the integration of Nile tilapia and Spinach in an aquaponic system.

Efficient water budgeting for various species will help in establishing database for providing practical solutions to the aquaculture sector's water crisis. Hence, a 90‐day study was conducted to evaluate the requirement of water for culture of Penaeus vannamei in inland saline groundwater. The earthen grow‐out ponds (0.1 ha) were stocked with postlarvae of P. vannamei (2.50 ± 0.01 g) at three different stocking densities, that is 30/m2 (T1), 45/m2 (T2) and 60/m2 (T3) respectively. The total quantity of water supplied and evaporation and seepage losses were measured on a daily basis. The rainfall and surface runoff were measured in the event of rainfall. The water quality parameters were analysed once in 10 days and were found to be within the permissible limit. The mean total consumption of water for T1, T2 and T3 was 2093.33 ± 6.66, 2099.30 ± 3.33 and 2092.96 ± 5.77 m3 respectively. The survival and yield of P. vannamei in treatments T1, T2 and T3 were 80.49 ± 0.61%, 72.06 ± 0.74% and 68.70 ± 1.45%; and 283 ± 1.53, 322 ± 3.46 g and 311 ± 3.79 kg respectively. The consumptive water use index was significantly less (p > 0.05) in T2 (6.53 ± 0.07 m3/kg) followed by T3 (6.74 ± 0.08 m3/kg) and T1 (7.41 ± 0.04 m3/kg). The water productivity of P. vannamei was significantly higher (p < 0.05) in T2 (0.153 ± 0.002 kg/m3) followed by T3 (0.148 ± 0.002 kg/m3) and T1 (0.135 ± 0.001 kg/m3). Considering the total quantity of water used and the shrimp produced from the earthen grow‐out ponds using inland saline groundwater, a stocking density of 45/m2 and a water budget of 6.53 m3/kg production of shrimp could be recommended as optimum.