Chrysochromulina fragilis is a unicellular haptophyte microalga in the genus Chrysochromulina, family Chrysochromulinaceae, class Prymnesiophyceae. The specific epithet fragilis — meaning fragile — may reference the delicate nature of the cell's scale ornamentation or the structural fragility of the haptonema, which can be easily damaged during preparation of electron microscopy specimens. Chrysochromulina species are nanoplankton organisms characterized by golden-brown chloroplasts, two flagella of approximately equal length, and a coiling haptonema that is a defining feature of the haptophyte lineage. C. fragilis is known from Norwegian and Swedish coastal marine environments, reflecting the thorough phycological sampling of Scandinavian waters that produced a substantial proportion of the currently recognized Chrysochromulina species. In these cold temperate to subarctic coastal systems, haptophytes including C. fragilis contribute to the spring and summer phytoplankton biomass. The species engages in photosynthesis utilizing the characteristic haptophyte pigment suite, and may supplement carbon acquisition through bacterivory or ingestion of dissolved organic matter. Chrysochromulina species as a group produce a variety of secondary metabolites, and some species form large surface blooms in stratified coastal waters. C. fragilis itself has not been associated with harmful bloom events in the published literature. It carries a conservation status of Not Evaluated under IUCN criteria. Continued ultrastructural, biochemical, and molecular studies of Norwegian Chrysochromulina species continue to illuminate the extraordinary diversity of this genus.