The sunray venus (SRV) clam (Macrocallista nimbosa), is an alternative shellfish aquaculture species to hard clams (Mercenaria mercenaria) for Florida. Production of high-quality hatchery seed is dependent on diet. This study was initiated to determine an optimal live microalgae diet and test the efficacy of commercially available microalgae concentrates as partial or complete replacements for live algae. Benefits were seen with multiple algal species combinations. Both clam species achieved highest growth and survival when fed a multi-species quad-algal live diet, although hard clams performed well when fed I. galbana and C. gracilis or I. galbana and P. lutheri. Neither species performed well with complete replacement diets, but showed good production with partial replacement diets. The fatty acid (FA) profile of clams reflected the FA profile of the fed diet. Clams fed multi-species diets of live algae had a well-balanced FA profile consisting of high n3/n6, EPA/DHA and EPA/ARA ratios. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection