Effect of Stocking Density on the Performance of Glass Eels (Anguilla mamorata) in an Indoor Culture System in Da Nang, Vietnam

The giant mottled eel (Anguilla marmorata) is a commercially valuable species that is commonly farmed in Vietnam. The survival rate of glass eels transitioning to the fingerling stage remains a challenge due to high mortality during the nursery phase. A 90-day experiment was conducted in triplicate to evaluate the effects of different stocking densities (200, 225, and 250 fish m-3) in an indoor system at a farm in Da Nang. Additionally, the eels were fed imported formulated feed from Taiwan. Throughout the experiment, water quality parameters were monitored: the water temperature averaged 27.96 ± 1.55°C, pH was 7.85 ± 0.18, DO was 6.29 ± 0.27 mg L-1, NH₃ was 0.22 ± 0.11 mg L-1, and NO₂⁻ was 0.06 ± 0.07 mg L-1. The survival rate was 61.36 ± 10.51% (ranging from 49.91% to 76.99%), and weight gain was 1.47 ± 0.05 g fish-1. Average survival rates (SR%) were recorded at 64.46 ± 9.97%. Overall, these results highlight that, for the nursery rearing of Anguilla marmorata using commercial feed, the optimal stocking density is 200 fish m-³.