Abstract This study investigated the growth performance parameters and parasites of Colossoma macropomum farmed in an aquaponic system constructed semi-dry wetland. Fingerling of C. macropomum (8.3 ± 0.9 g) were stocked in three experimental densities: 334, 668 and 1,002 g m− 3 g using four replicates by each treatment. The initial weight of C. macropomum was similar between fish densities tested. Electrical conductivity, nitrite, nitrate, potassium, and magnesium, turbidity, phosphate, total ammonia, and alkalinity increased with fish density. Dissolved oxygen concentrations showed a reduction, reflecting on fish growth. The final weight was different and that it was negatively impacted with increased density. The specific growth rate was similar between treatments with 334 and 668 g m− 3, but it differed significantly from treatment with and 1,002 g m− 3 of fish. The mean weight gain decreased with increased of fish density, while feed conversion ratio increased. Relative condition factor and survival of fish were not affected by the densities of fish. Ichthyophthirius multifiliis, Anacanthorus spathulatus, Notozothecium janauachensis and Mymarothecium boegeri were parasites found on C. macropomum gills in low abundance, which was not influenced by different densities of fish. Our results showed that fish yield was negatively impacted with increased density and differed between the by different density of fish, while the sanity was not affected.