Effects of stocking density on growth performance of Asian swamp eel Monopterus albus (Zuiew,1793) reared in recirculation aquaculture system

Abstract

This study aims to determine the carrying capacity of a recirculating aquaculture system (RAS) for rearing Asian swamp eel (Monopterus albus). Two experiments with two sizes of swamp eel (3.08±0.07 and 20.65±0.36 g/ind.) were conducted in different stocking densities. Results showed that during the experiment, water quality (temperature, pH, DO, TAN and NO2-) had slight fluctuation but still in suitable range for eel in all treatments. In the first experiment, four different densities of 1, 1.5, 2 and 2.5 inds./L was conducted in RAS with 80L culture tanks for 3 months. Results showed that there is no significant difference (p>0.05) in growth performance and survival rate of swamp eel between treatments. However, there is a significant difference (p<0.05) on FCR between treatment 1 ind./L (0.76±0.1) and 2.5 inds./L (0.56±0.05). The average survival rate in all treatments was above 68% and was not significant difference among the treatments. The second experiment was carried out in RAS with 250L culture tanks for culture period of 2 months. Growth rates are not differences between treatments, but survival of eel had significantly affected by stocking density. The lowest survival found in treatment 0.3 inds./L may be due to reducing feeding activities. The density of 0.4 inds./L gave the best survival rate (75%) but there was no significant differences with those of treatment 0.5 (69%) and 0.6 inds./L (70%). Low FCR was found in treatment 0.4 and 0.5 inds./L (1.85 and 1.88, respectively), however, there was no significantly differences between treatments (p>0.05).