The information on the nematodes of freshwater fishes of Japan published between 1905 and 2016 was assembled as a checklist in 2016 and 2017. The present paper updates the checklist based on the literature published between 2017 and 2021 and includes information on 12 nominal species and some unidentified species. The 12 nominal species belong to the following 6 families in the order Spirurida: Cucullanidae (1 species), Cystidicolidae (3 species), Physalopteridae (1 species), Quimperiidae (2 species), Raphidascarididae (1 species), and Rhabdochonidae (4 species). Over the 117-year period from 1905 to 2021, a total of 57 nominal species of the nematodes were reported from Japanese freshwater fishes, belonging to 32 genera in 18 families and 3 orders. The freshwater fishes reported as their hosts consist of 81 species and subspecies in 21 families and 9 orders.