Chroomonas baltica is a species of cryptophyte alga in the family Chroomonadaceae, as indicated by its specific epithet, associated with the Baltic Sea region and likely occurring in brackish and coastal waters of that area. Cryptophytes are an ancient and distinctive group of eukaryotic algae whose cells contain the evolutionary remnant of a red algal endosymbiont in the form of a nucleomorph — a reduced nucleus retained from the secondary endosymbiotic event that established their plastid lineage. Members of the genus Chroomonas are small, biflagellate cells typically olive-green to brown or blue-green in color, reflecting the mixture of chlorophylls, carotenoids, and phycobiliproteins present in their distinctive cryptophyte plastids. Chroomonas baltica is likely adapted to the low-salinity brackish conditions of the Baltic Sea, one of the world's largest brackish water bodies, where salinity gradients create unique ecological conditions and specialized communities of micro- and macroalgae. Cryptophytes are important components of Baltic phytoplankton communities, contributing to primary production and serving as food for microzooplankton. The species has not been assessed by the IUCN, consistent with the treatment of most microalgal taxa.