Homodiaetus is a genus of pencil catfishes native to South America.

There are currently four recognized species in this genus:[1] The distribution of Homodiaetus is restricted to the southeastern South America, from Uruguay to Paraguay Rivers in the west to the coastal drainages of the Rio de Janeiro State, Brazil.

H. banguela inhabits the São João River and H. passarellii is known from coastal basins in the State of Rio de Janeiro.

H. graciosa is distributed in coastal basins of southeastern Brazil in states of Paraná and São Paulo.

[2] Homodiaetus is currently distinguished from other genera of Stegophilinae by the combination of the origin of the pelvic fin midlength between the tip of the snout and the caudal-fin origin, the opercle with three or more odontodes, and the gill membranes confluent with the isthmus.