Hydrobiosis is a genus of caddisflies belonging to the family Hydrobiosidae. The genus was erected by Robert McLachlan in 1868.
The genus is found in New Zealand, the Chatham Islands, Australia (Tasmania, South Australia), and Fiji.
Hydrobiosis are carnivorous, with older instars consuming exclusively other invertebrates like simuliid and chironomid larvae. Early instars are detritivores that feed on fine organic matter such as dead leaves and wood, and algae fragments.