Chrysidiastrum catenatum is a species of chrysophyte alga (golden alga) in the class Chrysophyceae, documented from freshwater environments. It is a colonial organism in which cells are arranged in chains or filamentous sequences — as indicated by the specific epithet catenatum, meaning chain-like — distinguishing it from unicellular members of the group. Chrysophytes are photosynthetic flagellate algae characterized by their golden-yellow to brown plastids containing chlorophyll a and c along with fucoxanthin as the dominant accessory pigment. Colonial chrysophytes such as Chrysidiastrum represent an intermediate level of cellular organization between solitary unicells and true multicellular organisms. The colony provides some advantages including reduced grazing mortality and potentially improved motility. Chrysidiastrum catenatum has been documented from freshwater phytoplankton in European lakes and is part of the diverse chrysophyte flora characteristic of oligotrophic to mesotrophic freshwater bodies in temperate and boreal regions. Golden algae contribute to primary production and serve as food for zooplankton and heterotrophic flagellates. Some chrysophytes can form resistant resting stages called stomatocysts or statospores, which are useful as paleoecological indicators in lake sediment cores. The species has not been assessed by the IUCN.