Four unidentified new strains of Pavlovophyceae [Pavlova sp. AC 250 (M), Pavlova sp. AC 248 (Psh), Pavlova sp. AC 251 (Pth), Pavlova sp. AC 538 (Psm)] and two known species [Pavlova pinguis (Ppi), Rebecca salina (ex Pavlova salina, Rsa)] were characterized (productivity, size, dry weight, ash, gross composition, fatty acids, sterols) and their nutritional value in bispecific diets were evaluated both on Crassostrea gigas and Pecten maximus larvae. All microalgae exhibited poor food value for C gigas larvae. P. pinguis and R. salina did not sustain any growth, like the control starved larvae. No exo-toxicity of P. pinguis and R. salina was detected. These two species were weakly ingested by C. gigas larvae, while the four other pavlovophytes were effectively grazed. When used as food for P maximus larvae, P pinguis and Psh led to poor development. In contrast, a diet with Pfl resulted in significantly better growth than the control.