Results also showed that the preferred prawn size of marble goby fingerlings of average weights of 0.26–4.18 g was small (9–12 mm) with positive electivity index of 0.19–0.33, and the shift from small- to medium-size (12–14 mm) prawns was slow. The present study has demonstrated the feasibility of using rice field prawns as live foods to nurse marble goby fingerlings.