An investigation on the fluctuation of water quality in garden canals cultures of freshwater prawn in Tra On district, Vinh Long province.

Abstract

Freshwater prawn (Macrobrachium rosenbergii) is one of important aquaculture species in Vietnam. With culturing freshwater prawn, water quality is important because maintaining balanced levels of water quality parameters is fundamental for both the health and growth of culture freshwater prawn. Good water quality by proper management will help prevent freshwater prawn diseases and create an environment for better growth and higher survival rate. The experiment on freshwater prawn culture were carried-out in Tra On District, Vinh Long Province. The area each ditch 3000 m2 (6 PL15/m2). Prawns were fed by commercial feed (40% protein) combined with fresh feed. Prawns were harvested after 6 months. The results showed that the water quality in cultured system such as water temperature 26.5 - 31.9 oC, water pH 7.0 - 8.2, transparency 25.9 - 38.4 cm, dissolved oxygen 4.9 - 5.6 mg/L, P-PO43- 0.1 - 1.2 mg/L, N-NH4+ 0.5 - 0.9 mg/L , N-NO2- 0.06 - 0.8 mg/L, COD 25.7 - 69.4 mg/L, chlorophyll-a 24.6 - 80.3 µg/L and H2S 0.02 - 0.1 mg/L were acceptable values for the freshwater prawn growing. The survival rate was recorded from 28.7 to 31.5% and yield ranged from 517 to 567 kg/ha.