Nitrogen and Phosphorus Waste Production from Different Fish Species Cultured at Floating Net Cages in Lake Maninjau, Indonesia

摘要

Background and Objective: Aquaculture operations that use floating net cages have become one of the primary mean of intensive fish-culture in Lake Maninjau. The fish-culture species studied were Cyprinus carpio ( C . carpio ) (T₁), Oreochromis niloticus ( O . niloticus ) (T₂), Osphronemus goramy ( O . goramy ) (T₃) and Clarias gariepinus ( C . gariepinus ) (T₄). The objective of the research was to estimate the nitrogen (N) and phosphorus (P) loads into Lake Maninjau. Materials and Methods: The capacity of floating net cages was approximately 32 m³ (4×4×2 m) with densities of 32 fish m^?3 in triplicate groups. Approximately 1,500 kg of feed was used in each cage during the experiment. The difference of N and P loads from different fish species were analyzed using one-way ANOVA (SPSS 16.0) computer software. Results: The total N loads into the water bodies from T₁, T₂, T₃ and T₄ were estimated at 37.93±2.59, 49.90±5.17, 45.90±4.18 and 20.35±4.12 kg t^?1 of fish production, respectively. The P load was estimated to be 18.30±0.12, 20.01±0.99, 22.60±0.80 and 13.93±1.47 kg t^?1 of fish production, respectively. Every ton of feed consumed by each fish species will contribute as much as 38.26±2.55, 35.68±1.69, 32.12± 0.39 and 48.99±2.35 kg N load into the water bodies, respectively. The P load was 11.45±2.43, 9.11±0.21, 8.34±0.04 and 12.51±0.30 kg, respectively. Conclusion: The C. gariepinus species is preferred for aquaculture operations at Lake Maninjau, because it minimizes N and P load releases into water bodies which can maintain sustainable aquaculture operations.