Abstract
Polyculture is a sustainable aquaculture system because it can reduce environmental pollution and increase feeding efficiency. The purpose of this study was to analyze the performance of growth, biomass and food competition for tilapia as the main commodity and lemeduk fish as a secondary commodity with a polyculture system in floating net cages. The research method used a Completely Randomized Design (CRD) consisting of 5 treatments and 3 replications, namely: treatment A (60 tilapia fish), Treatment B (40 tilapia fish + 20 lemeduk fish), Treatment C (30 tilapia fish + 30 lemeduk fish), Treatment D (20 tilapia fish + 40 lemeduk fish), and Treatment E (60 lemeduk fish). The research container uses floating net cages with a size of 0.5 × 0.5 × 1m. Parameters observed were absolute length growth, absolute weight growth, specific growth rate, biomass production, competition index, and water quality. The results showed that the polyculture system of tilapia and lemeduk at different stocking densities had a significant effect on absolute length growth, specific growth rate, biomass production, and had low competition between tilapia and lemeduk. The best treatment was found in treatment B (N 40+ L 20) and treatment C (N 30+ L 30) with absolute length growth value 3.20 cm±0.17, specific growth rate 3.83%±0.36, biomass of tilapia 94.36 g/0.5m2±16.45 and total biomass 100.69 g/0.5m2±5.49. Hence, the polyculture system is better than the monoculture system and the absence of competition between tilapia and lemeduk in using food.
Highlights
The growth of floating net cages in flooded waters is very rapid and often causes environmental problems
Tilapia is one type of fish that has economic value and important commodity in the freshwater fish business because tilapia has beneficial properties, such as: easy to breed, fast growth, and easy to grow in intensive aquaculture systems [1]
The competition index obtained in this study shows that the competition index for tilapia and lemeduk is negative in all treatments (Table 2)
Summary
The growth of floating net cages in flooded waters is very rapid and often causes environmental problems. The impact of fish farming activities in cage culture can cause the water quality of stagnant waters to decrease. The decrease happened because of the leftover feed waste. The majority of fish farming systems in cage culture use a monoculture system. Just one type of fish that we can keep is Tilapia. Because Tilapia is continuous demand and availability of seeds. Tilapia is one type of fish that has economic value and important commodity in the freshwater fish business because tilapia has beneficial properties, such as: easy to breed, fast growth, and easy to grow in intensive aquaculture systems [1]
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