Parambassis siamensis is a species of freshwater fish in the Asiatic glassfish family Ambassidae. It is native to the mainland Southeast Asia in Thailand, Cambodia, Vietnam, and Laos; records from Singapore and Java (Indonesia) probably are introductions. Its range includes the Mekong, Mae Klong, and Chao Phraya basins. It grows to 7.5cm (03inches) standard length, although typical length is about 4cm (02inches).