Utilization the Aquatic Plants as a Filtration Media in A Closed Bio-Aquatic System to Improve Water Quality and Common carp Growth Performance

The experiment was conducted in the animal production field, College of Agriculture, Tikrit University, for the period from 14/6/2022 to 14/8/2022 inside a semi-exposed building with three treatments. Each treatment included three replicates, and each replicate included (6) fish in a closed bio-aquatic system, by weight 13.75±1.09, a filtration tank representing the mechanical and biological filter in an intensive aquatic system with a capacity of 100 liters each, two aquatic plants were grown Water thyme (Hydrilla Verticillata), Torpedo grass (Panicum Repens), except for the control treatment, which was similar to all treatments except for the presence of aquatic plants. The water was treated in a mechanical filter unit through sponge layer, then directing the water to the biological treatment by means of crushed gravel, in addition to the aquatic plants to filter the dissolved organic pollutants. The results showed a significant effect of aquatic plants at (p ≤0.05) on pH, Cloredait (Cl) nitrate (NO3,) nitrite (NO2), and ammonia. Water properties reflect to the biological system of organisms. There was a significant improvement in gain weight (G.W), specific growth rate (SGR), and feed conversion efficiency (FCR) for treatments T2 and T3 compared with control treatment. While, the result of the correlation or interactions between water characteristics with growth parameters for Common carp fish showed significant effects at (P ≤0.05) and (P ≤0.01) level.