Riga was a Monean, a species that live under the sea on their ocean planet.
When USS Voyager visited the planet, the Moneans asked for help, since their ocean was losing containment. Tom Paris and Riga investigated and discovered that the Monean's mining operations in the ocean were the problem. Riga gave this information to Burkus, a government offical. Burkus said he would include it in a report.
Riga decided to do something about the situation himself, and he and Paris tried to disable the mining operations. They were unsuccessful, and Paris was demoted for disobeying Captain Janeway's orders. Riga's efforts to persuade the Monean Government to deal with the problem fell on deaf ears. (VOY: "Thirty Days")
Riga was played by Willie Garson.