Najas tenuissima, also known as Delicate Water Nymph, is an annual herbaceous aquatic plant native to freshwater habitats such as lakes, slow-moving rivers, and ponds in Finland, European Russia, the Russian Far East, and Japan. It is submerged and rooted in the sediment, with slender stems that can grow up to 40 cm long. The leaves are very narrow, up to 1 cm long, and arranged in opposite pairs along the stem. This species is not commonly cultivated but can be used in aquariums and water gardens.

Delicate Water Nymph is valued for its ability to oxygenate water and provide habitat for aquatic organisms. It is a low-maintenance plant that requires submerged conditions, clear water, and full sun to part shade. It is not known for any significant problems or diseases, but it can be sensitive to water pollution and changes in water levels. In cultivation, it can be grown from seeds or fragments of the plant. It should be monitored to ensure it does not outcompete native species in non-native environments.CC BY-SA 4.0