Cân bằng vật chất dinh dưỡng trong hệ thống tuần hoàn nuôi cá trê vàng (Clarias macrocephalus)

Abstract

The study was carried out with bighead catfish (Clarias macrocephalus) reared in a recirculating aquaculture system (RAS) that consisting of 100-L culture tank, 30-L swirl separator, 60-L sump tank and 70-L moving bed biofilm reactor. Four different sizes (10 g, 30 g, 70 g and 100 g) of fish was stocked at density of 100 fish/tank then fed to ad libitum rate by floating pellets (41% crude protein) for 15 days. In the total of feed supply, retention in fish accounted by 25.4-32.7% in dry matter (DM) and 28.6-42.7% in nitrogen (N); waste production by fecal loss made up 8.8-23.1% of DM and 14.7-40.0% of N; and non-fecal loss accounting for 12.8-15.3% of DM and 36.7-38.4% of N. The remaining was consumed by bacteria and lost by evaporation and seepage. Results also revealed that to produce 1 kg of fish, it was necessary to provide 780.6-1,033.7 g DM containing of 48.5-64.3 g N. Of which, nutrient accumulation in fish was 255.2-262.3 g DM and 20.0-21.1 g N; released in waste production of 525.4-771.5 g DM and 27.5-44.3 g N.