Evaluation of the effectiveness of bighead catfish (Clarias macrocephalus) in recirculation system combined with waste treatment

Abstract

The objective of the study was to evaluate the bighead catfish (Clarias macrocephalus) efficiency in recirculation aquaculture system (RAS) combined with waste treatment. The experiment was carried out in a recirculating aquaculture system with a volume culture tank of 4 m³ for 4 months. The RAS consists of 4 culture tanks with a volume of 1 m³/tank, 350-L swirl separator, 350-L sump tank and 2m³ moving bed biofilm reactor and a water lettuce tank (surface area 2 m²). Fish with an average weight of 11 grams/fish are cultured with a density of 1,000 fish/m³. The fish were fed twice a day at ad-libitum rate with 41% protein pellet. The results showed that cultured in the RAS with a scale of 4m³, the fish reached 141.0-157.8 g/fish, survival rate 73.74-88.3%, yield 100.7-141.8 kg/m³ and FCR is 1.02-1.29 after 120 days of culture. Growth in weight (y: in grams) of Clarias macrocephalus by day of culture (x: in days) is represented by the equation: y = 1.2397x - 3.4465 (R² = 0.9697) with a special growth rate weight 2.05% / day. In the 1 kg of feed supply (by dry matter, containing 52.2 g N), waste production fecal loss and total suspended solids by made up 19.78% of N (containing 10.32 g N); and non-fecal loss accounting for 40.6% of N (containing 21.19 g N). The moving bed biofilm tank could reduce 32.5% of TSS, 3.42% of COD, 6.49% of PO₄^3- and the water lettuce tank could reduce 24.7% of TSS, 0.37% of COD, 17, 55% of NO₃^-, 5.34% of PO₄^3-, 12.82% of TN of the RAS. Water use for 1 kg bighead catfish in RAS is 0.2 m³.