Four families (1 fresh water and 3 tidal oribatid mite families), 8 genera and 19 species of aquatic oribatid mites were listed from Japan. These four families were Hydrozetidae inhabiting fresh water only, and Ameronothridae, Selenoribatidae and Fortuyniidae as tidal mites, and were not included in Ohkubo et al. (2015) as a checklist of soil-inhabiting oribatid mites of Japan. We determined that the original combination Rhizophobates shimojanai Karasawa & Aoki, 2005 was appropriate.