It is important to know the impact of sediment type on feeding and growth performance of sea cucumbers in aquaculture which is getting more importance due to the critical decrease in valuable stocks in all seas. The purpose of the present study is to investigate the effect of grain size on growth performance of juvenile sea cucumber (Holothuria tubulosa) under aquaculture conditions. In the present study, the growth performance of juvenile sea cucumber (H. tubulosa) on 3 different grain sized sediment has been investigated in laboratory conditions for 61 days. Sea cucumber juveniles (35.02 +/- 0.52 g) were placed into the 200x50x50 cm aquaria by 350 g m(-2). Natural crushed quartz sediment in different grain sizes (1 mm, 3 mm, 7mm and 0.2 mm (control)) were placed inaquariaby 10cm height. Final mean weight of the juveniles in sediment groups1 mm, 3 mm, 7 mm and 0.2 mm (control) were recorded as 49.18 +/- 0.94 g, 44.23 +/- 0.35 g, 40.72 +/- 0.53 gand 39.57 +/- 0.50 g, respectively. Specific growth rate of juveniles among sediment groups were ranged between 0.20% day(-1) (Control) and 0.53 % day(-1) (1mm). Overall, best growth performance was found as significant in 1 mm sediment group.