Preliminary assessment of large-scale co-culture of sandfish (Holothuria scabra) with the Babylon snail (Babylonia areolata) in earthen ponds and in raceways

Abstract

Holothuria scabra (sandfish) and Babylonia areolata were trialed in two large-scale co-culture experiments. Experiment 1 assessed co-culture in 4 × 400 m2 earthen ponds where Babylonia were cultured in a central pen at a density of 400 individuals/m2 with sandfish occupying the remaining pond space at 1.1 individuals/m2. Sandfish grew from 18.20 ± 6.67 g to 119.03 ± 17.74 g in 92 days and Babylonia (fed trash fish in both experiments) grew from 0.90 ± 0.38 g to 4.93 ± 1.44 g, but Babylonia growth was not increased in co-culture compared to monoculture. Water and sediment quality varied between co-culture and monoculture ponds. Neither showed clear improvement due to sandfish culture. Experiment 2 compared non-segregated sandfish-Babylonia co-culture with Babylonia monoculture in 20 m2 concrete raceways. Sandfish were cultured at 2 individuals/m2 and Babylonia at 300 individuals/m2. Sandfish grew up to 1.91 g.day−1 with 100% survival. Babylonia weight gain was significantly greater in co-culture raceways (3.35 ± 0.64 g over 61 days), which was double that of Babylonia in monoculture. Substrate total N was reduced by 20% in co-culture compared with monoculture (p =.032). This provisional study of commercial scale sandfish-Babylonia co-culture demonstrates culture compatibility, providing a basis for further system development.