Aquaponics is an innovative sustainable farming method that integrates aquaculture with hydroponics. In an aquaponic system, the nutrient rich water from fish is used to grow plants which in turn purify water for fish. It is an environmentally friendly option for fish and plant production, addressing the increasing demand for food while being a great solution in arid and semi-arid regions where water resources are limited. The success of aquaponics systems depends on achieving a balance between fish density, water quality, and nutrient availability for plant growth. This study aimed to determine the optimal stocking density of goldfish (Carassius auratus) to maintain water quality while promoting growth performance in both goldfish and basil (Ocimum basilicum) in a flood-and-drain aquaponic system. Three goldfish densities, 0.5 kgm-3, 1.5 kgm-3, 2.5 kgm-3 (low, medium, and high, respectively) were examined to assess their effects on water quality and growth performance of goldfish and basil. Water quality parameters such as dissolved oxygen, pH, temperature, conductivity, salinity, Total Ammonia Nitrogen (TAN), Nitrate-N, Nitrite-N were tested while the growth performances were observed based on the initial and final weights of fish and plants. At the end of the experiment, the plant nutrient biomass was analyzed to assess plant health.
Our findings highlighted that medium stocking density achieved an optimal equilibrium, maintaining water quality within safe thresholds for fish while providing adequate nutrients for plant growth. Goldfish displayed improved health metrics in low and medium densities while plants exhibited a better growth in medium densities compared to low and high densities. This study illustrates the importance of optimal stocking density of fish in aquaponic systems to maximize productivity and sustainability, providing insights to improve the efficiency of aquaponic farming.