Aquarium introduction: The main requirement for stocking aquatic life in an aquarium is the quality of the water. The water source is not allowed to contain pollutants, such as sewage and industrial waste; the gas in the water must be balanced with the atmosphere to ensure sufficient oxygen in the water; and at the same time, avoid supersaturation of nitrogen. In a recirculation system, water treatment must not only ensure the clarity of the water, but also the purification of excreta. The aquarium's marine organisms are stocked in artificial seawater. The advantage of artificial seawater is that it is free of disease-causing organisms and contaminants.