Aquaponics system integrating tilapia (Oreochromis niloticus L.) and Tomato (Solanum lycopersicum L.) for water reuse in small-scale production

Abstract

Aquaponics is a closed production system that integrates the technique of aquaculture with hydroponics, that is, the combined production of fish and plants without the use of the soil. The aim of this research was to evaluate the quality and reuse of water in aquaponic crops with tilapia (Oreochromis niloticus) and tomato (Solanum lycopersicum) in the aquaculture farm of the National Agrarian University located at km 12 of the North Pan-American Highway, Managua, Nicaragua. The methodology used was developed at various times: installation of the aquaponic system with a tank of 1,000 liters of water capacity (1 m3) of aquaculture origin, mechanical filter, biological filter and planting bed with tomato plants. For the determination of quality, the following parameters were evaluated: concentration of ions, H+ (pH), dissolved oxygen, biological oxygen demand, ammonium (NH4+), nitrites (NO2-), nitrates (NO3-), temperature, turbidity and electrical conductivity. Water samples were taken at four specific points in the system. The pH, temperature and electrical conductivity were measured with pocket multiparameter equipment, dissolved oxygen with a field oximeter, turbidity was measured with a graduated Secchi disc every 10 cm; and using colorimetric solutions, NH4+, NO2- and NO3- were determined. The biological oxygen demand in five days was analyzed at the laboratory level. It was observed that all the parameters do not exceed the reference values proposed by technical documents and there were only fluctuations in the stages of water exchange and fish feeding. For the biological oxygen demand in five days there is no technical reference, therefore, it is an important contribution to verify the good behavior of the oxidation processes. These results allow us to conclude that the water is reusable, that the system is efficient and that the production of tomatoes and tilapia is viable with this type of production system.