Effect of hydraulic loading rate on the growth of koi carp (Cyprinus carpio var. koi.) and Gotukola (Centella asiatica (L.)) using phytoremediated aquaculture wastewater in aquaponics

The study evaluates optimum hydraulic loading rate (HLR) based on the fish and plant production performance and nutrient removal percentage in aquaponics. The growth of Gotukola (Centella asiatica (L.))—a leafy vegetable as well as traditional medicinal plant—and koi carp (Cyprinus carpio var. koi.)—a high demand ornamental fish—were evaluated at three different HLRs, viz. 2.6 m day−1 (T1), 7.8 m day−1 (T2), and 13.0 m day−1 (T3). Treated aquaculture wastewater was utilized in a combination of the freshwater in 1:1 ratio with 2.1 kg m−3 fish stocking density. The highest fish mean length; weight; feed conversion ratio; specific growth rate; NH3, NO2−, and NO3− removal percentage; and plant growth parameters were observed. Considering fish (koi carp) and plants (Gotukola) growth parameters as well as nutrient removal percentages, a HLR of 7.8 m day−1 was found to be the optimum in aquaponics.