The floating net cage (FNC) system for fish farming has rapidly developed in Indonesia's reservoirs and lakes. Many of these activities have surpassed the waters' carrying capacity and are considered responsible for a decline in water quality. Pollution resulting from aquaculture practices originates from uneaten feed and fish excretion discharged into water ecosystems. Consequently, there is a necessity for sustainable aquaculture technology that can minimize FNC waste discharged into aquatic environments. This research aims to describe the design of eco-friendly FNC and to assess the decrease in phosphorus and organic matter loading. The research was performed in Cirata Reservoir from October- December 2019. The cage utilized was 6 x 6 meters. The fish seeds utilized weighed 15 kg, with an average weight of 11.5 g/fish, and a density of 7 fish/m3, resulting in a total of 775 fish. The meal provided constituted 5% of the fish's weight and was administered three times daily. The mean growth rate of tilapia fish cultivated was 1.75 g/day, with a feed conversion ratio (FCR) is 1.54, resulting in a production of 124 kg. The implementation of a bottom-tight pond effectively diminished the total organic matter (TOM) pollution load by 200 kg and total phosphorus by 50.8 kgP for each tonne of fish harvested.