The main objective of this study was to evaluate the effect of the addition of Rhodomonas salina in the diet of Pecten maximus on growth, survival and metamorphosis success in relation to biochemical content. Food quality is an essential factor in the success of larval, post-larval and juvenile development. A diet rich in polyunsaturated fatty acids present an advantage for growth, survival and metamorphosis success. Larvae and post-larvae fed with the diet containing R. sauna showed a higher accumulation of arachidonic acid (20:4n-6) and generally a lower concentration of docosahexaenoic acid (22:6n-3). Addition of R. sauna in diet was related with higher level of eicosapentaenoic acid (20:5n-3) in larval stages, but lower level in post-larvae. Addition of R. salina seemed to be advantageous during larval stages by a higher accumulation of triacylglycerol associated with an earlier appearance of metamorphosis. The composition of sterol observed in larvae fed with an addition of R. sauna showed a high level of brassicasterol. Advantage of the preferential accumulation of brassicasterol with the addition of R. salina is not clear but other studies suggest that brassicasterol can replace cholesterol in some functions. Our results suggest that addition of R. salina at larval stages could be advantageous in the aquaculture hatchery by a more rapid passage of P. maximus in the nursery. (C) 2010 Elsevier B.V. All rights reserved.