V. Fucoxanthin is one of the most abundant carotenoids in nature. It is a major carotenoid in heterokont and haptophyte groups of algae that includes  20 thousand species. Fucoxanthin also has many beneficial health effects including anticancer, antihypertensive, anti-inflammatory, and antiobesity effects. Microalgae are a promising source of fucoxanthin for commercial production. To find the most efficient fucoxanthin producing strains of microalgae, we isolated seven new strains of microalgae from multiple locations in Russia and Vietnam and studied their growth parameters and fucoxanthin content. Based on these results we isolated a novel strain of Mallomonas sp. (Synurophyceae) with the highest known content of fucoxanthin in biomass (26.6 mg g− 1DW). The analysis of available data on heterokont and haptophyte algae shows that three groups of algae are the most promising for commercial production of fucoxanthin: diatoms (up to 21.67 mg g− 1DW), Synurophyceae (up to 26.6 mg g− 1DW) and Prymnesiophyceae (up to 18.23 mg g− 1DW).