The production of high-quality seedlings is important to achieve better productivity in horticulture. Despite being well developed in conventional agriculture, there are few studies on aquaponic systems. The substrate choice in this integrated culture affects plant and economic feasibility. This study verified the effects of using Euterpe oleracea residue as a substrate for Coriandrum sativum seedling production in an aquaponic system with tambaqui, Colossoma macropomum. Five mixtures of Euterpe oleracea offal (0%, 25%, 50%, 75% and 100%) with coconut fiber, nourished by aquaponic wastewater, were evaluated. Water quality, fish and plant performance were analyzed during an 18-day experiment. Although total ammonia decreased from 5.17 mg L⁻¹ to 0.64 mg L⁻¹, nitrite and nitrate did not exceed 1 mg L⁻¹ and 3 mg L⁻¹, respectively. C. macropomum mean weight gain was 118.79 g and achieved high food assimilation, with a 0.86 feed conversion rate. Mean blood hematocrit (30.20 ± 5.99%) and glucose (59.5 ± 10.06 mg dL⁻¹) indicates good physiological status of the C. macropomum. The use of the Euterpe oleracea offal mixture at 50% decreased by half the total fresh mass of Coriandrum sativum, down to 1.12 ± 0.30 g, but did not decrease dry mass (p > 0.05). When the mixture was above 25%, plant and leaf length were 8 cm and 3 cm smaller, respectively, and the number of leaves and stem base diameter were reduced by 34% and 40%, respectively. We do not recommend using more than 25% of Euterpe oleracea offal with coconut fiber for Coriandrum sativum seedling production in an aquaponic system.

This study evaluated cherry tomato seedling production using pirapitinga RAS wastewater as the sole nutrient source in four substrate formulations: T1 (sand, gravel and coconut fiber), T2 (sand and gravel), T3 (gravel and coconut fiber), and T4 (sand and coconut fiber). No differences were observed for germination quality, germination percentage, seedling vigor index, germination vigor index, moisture content, total wet biomass, total dry biomass, or mortality. For small plants, leaf number (LN) was higher in T2 and lower in T4, while root length was greater in T3. The number of medium plants was higher in T3 and lower in T4; LN was higher in T1 and T2 and lowest in T3. For large plants, LN was higher in T1 and T2 and lower in T3; total length was higher in T1 and lower in T3 and T4. Visual differences in substrate water retention were observed: T4 exhibited rapid surface drying, T1 and T2 showed moderate moisture persistence, and T3 maintained surface water. Leaf yellowing was observed after 25 days, suggesting possible nutrient limitation or reduced nutrient availability at the measured pH. These findings indicate that substrate physical characteristics influence early seedling growth performance, whereas pirapitinga RAS wastewater can serve as a viable nutrient source.