Shellfish Diet 1800 is a unique mix of five marine microalgae - Isochrysis, Pavlova, Tetraselmis, Thalassiosira weissflogii and Thalassiosira pseudonana - species that have demonstrated success with a wide variety of freshwater and marine shellfish, including: oysters, clams, mussels, scallops, crustaceans, soft coral.