Pseudanabaena limnetica is a slender, filamentous cyanobacterium commonly found in the plankton of freshwater lakes, reservoirs, and ponds worldwide. Its single-celled, bead-like trichomes are loosely arranged and lack heterocysts, distinguishing it from nitrogen-fixing relatives. This cyanobacterium can form dense blooms in eutrophic water bodies and contributes to primary production in the water column.