Sulphated polysaccharides exhibit a range of activities which promote health and growth benefits to aquaculture species. One class of sulphated polysaccharides derived from marine algae is fucoidan, which is suggested to exhibit an affinity to the negative muscle growth inhibitory protein myostatin. Addition of fucoidan to the diet of fish therefore may lead to enhancements in growth through inactivation of the myostatin protein. To examine the growth enhancing potential of this sulphated polysaccharide, fucoidan extracts from Undaria pinnatifida were added to the diet of juvenile barramundi, Lates calcarifer. The fucoidan extract was of 86% purity and included in two treatment diets at 5 g kg−1 (0.5%) and 10 g kg−1 (1%) respectively. Fish were fed the diet for 52 days. At the end of the feeding trial, barramundi fed with the 1% fucoidan inclusion diet exhibited enhanced growth with significantly increased lengths, weights and muscle fibre area (hypertrophy) when compared to the 0.5% fucoidan inclusion diet and the non-fucoidan control diet. This research suggests that addition of fucoidan to the diet of fish may have growth promoting effects.