First assessment of the potential for coculture of sandfish (Holothuria scabra) with Babylon snail (Babylonia areolata) in Vietnam

The potential for the coculture of sandfish, Holothuria scabra and Babylon snail, Babylonia areolata was investigated. Sandfish (weight 1.87 ± 0.41 g) were cultured at low (25 ind/m²; 46.75 g/m²), medium (50 ind/m²; 93.5 g/m²), and high (100 ind/m²; 187 g/m²) densities in monoculture and in coculture with Babylonia at a density of 400 ind/m² (208 g/m²). In monoculture, sandfish were provided with 1 g m⁻² day⁻¹ commercial prawn starter feed. In coculture, trash fish provided for Babylonia (5% total wet weight per day) was the only food input. Sandfish survival over the 84-day experiment period was reduced in coculture treatments (77.60 vs. 97.22%) but was in line with expected survival rates (80–90%) of commercial sandfish culture. Mean sandfish weight gain and absolute growth rate were around 37% greater in coculture (mean weight gain 13.42 ± 2.90 g vs. 9.77 ± 2.54 g over 84 days). No differences in Babylonia growth rate or survival were evident between sandfish density treatments. Sediment organic matter content did not differ significantly between monoculture (0.43 ± 0.03%) and coculture (0.55 ± 0.06%) treatments, but the latter had elevated concentrations of ammonia. Results provide a basis for further development of land-based pond coculture systems for sandfish and Babylonia.