Salvinia natans is a small, annual or short-lived perennial floating fern native to Europe and Asia, where it occurs in slow-moving rivers, ponds, lakes, and rice paddies across a wide temperate range. Each plant node bears two floating oval leaves and one finely dissected submerged leaf that functions as a root, absorbing nutrients from the water. The floating leaves are covered in water-repellent hairs, keeping the surface dry, and have a distinctive bright to medium green coloration. Salvinia natans is notable for its tolerance of cooler temperatures, remaining active at 15 °C — significantly cooler than most tropical floating plants — making it a rare option for cold-water and unheated aquariums. In autumn or when temperatures drop below about 10 °C, the plant produces spores and dies back, completing its lifecycle in temperate outdoor ponds before reappearing from spores the following spring. In consistently warm aquarium conditions it can persist as a perennial. Compared to Salvinia auriculata and the invasive S. molesta, S. natans is smaller, grows less aggressively, and is generally considered non-invasive outside its native range. It provides surface cover, shade, and nutrient uptake and creates a hiding place for surface-dwelling fish, fry, and shrimp. This species is an ideal choice for aquarists seeking a floating plant for temperate or subtropical setups, species tanks with cooler-water fish, or as a seasonal plant in outdoor ponds in temperate climates.
