The Tesnians are a spacefaring species from the planet Tesnia. They could breathe a nitrogen-oxygen atmosphere, but required six hours of boron gas a day.

In 2151, the Enterprise rendezvoused with a Tesnian vessel, which suffered critical systems malfunctions and crashed on an asteroid just before it docked. Subcommander T'Pol later discovered that the ship had been struck by a microsingularity. The Enterprise was able to rescue the crew and transport them back to their homeworld. (ENT: "Shuttlepod One")