阿尔氏长须

The <em>Esomus ahli</em> is a freshwater fish belonging to the family Danionidae, a group of small, active cypriniform fishes distributed primarily across South and Southeast Asia. Adults of this species typically attain a maximum length of approximately 6 cm. Danionids are characterised by their streamlined bodies, often with prominent lateral stripe colouration, and are typically shoaling fishes of riverine and lentic environments. The genus <em>Esomus</em> is notable for its elongated pectoral fins, which in some species are proportionally large relative to body size. <em>Esomus ahli</em> is likely associated with still or gently flowing freshwater habitats — ponds, rice paddies, lakes, and slow streams — typical of danionid species across tropical Asia. Details of habitat and range for this species remain limited in the ichthyological literature. Many species in the genus are surface feeders, consuming small insects, zooplankton, and other material that falls onto or near the water surface. The species is named in honour of Ernst Ahl, a German ichthyologist who described numerous freshwater fish species during the early twentieth century. Small danionids like <em>Esomus ahli</em> typically serve as important prey items for larger piscivorous fishes, wading birds, and other predators in their native freshwater ecosystems.