Optimization of hydraulic loading rate in aquaponic system with Common carp (Cyprinus carpio) and Mint (Mentha arvensis)

• Common carp and Mint grew well and found to be suitable for culture in aquaponic system.
• Hydraulic loading rate (HLR) of 6 m day−1 is most optimum for the rearing of Common carp and Mint in aquaponic system.
• No water exchange was done throughout the experiments. However, only evaporated water loss was maintained by addition of new water, which showed water use efficiency of the system. No aquaculture effluents were discharged into the environment which ensured that aquaponics is an environment friendly system.
• The recirculating aquaponic system proved that it is not only a successful method for food crop production, but also a beneficial system to reuse aquaculture wastewater and safeguard the water resources of the country.

Aquaponics is the combined culture of fish and plants in recirculating aquaculture systems, considered to be an innovative, eco-friendly and sustainable technology. The present study on bio-integration of Common carp and Mint in aquaponic system was aimed at determining the optimum hydraulic loading rate (HLR) for the aquaponic system. Three treatments having different HLRs viz., T1 (3 m day−1), T2 (6 m day−1) and T3 (12 m day−1) were compared and their effect on fish growth, survival, mint growth, yield and various water quality parameters were observed to find the most efficient HLR for Common carp and Mint in aquaponic system. Different HLRs showed significant effect on fish growth in terms of length and weight gain, survival, specific growth rate (SGR). Higher growth rate was observed in treatment T2 (6 m day−1) as compared to other treatments and control having different HLRs. Mint growth rate at the end of both the harvests showed significant variation and got affected by different HLRs with better results obtained in treatment T2 (6 m day−1). Overall water quality parameters, nutrient removal and biofilter performance were better at HLR 6 m day−1 i.e., treatment T2. Hence, HLR of 6 m day−1 can be recommended for culturing Common carp and Mint in aquaponic system.