Nitrogenous compounds, fish and plant growth were impacted by hydraulic loading rates on the aquaponic bed with açai seed (Euterpe oleracea)

The study investigated the hydraulic loading rate (HLR) for an aquaponic bed with açai seed in a hybrid system with tambaqui (Colossoma macropomum). 240 juveniles tambaqui with an initial average weight and length of 21.8 ± 7.74 g and 11.28 ± 6.88 cm were distributed in 12 independent aquaponics systems. HLRs were calculated and four different rates of 1.4, 5.4, 13.6 and 23.3 m3 day−1 m−2 were established, all in triplicate and applied for eight weeks. Water quality, as well as fish growth performance, germination and growth of açai seeds were evaluated. HLRs modified dissolved oxygen, pH, alkalinity, conductivity, total dissolved solids, ammonia, nitrite, and nitrate between treatments. Ammonia removals (mg h−1) were 2.6 times higher in HLR of 23.3 and 13.6 m3 day−1 m−2. Phytotechnical performance of açai seedlings (germination) and fish growth performance were significantly reduced at HLR 1.4 m3 day– 1 m−2. The final weights of the tambaqui were significantly higher (116.3 ± 5.77 g) at HLR 5.4 m3 day−1 m−2. Given the results observed, the HLR for improved system performance was 13.6 m3 day−1 m−2, considering the experimental model presented in the present study. [Display omitted] •HLRs significantly modified the water quality parameters.•Greater ammonia removal in treatments 23.3 and 13.6 m3 day−1 m−2.•HLR 1.4 m3 day−1 m−2 reduced plant growth performance.•HLR 5.4 m3 day−1 m−2 improved fish growth performance.