Smooth glassies are small silver fish with translucent bodies. Their fins are almost completely translucent, with a deep notch in the centre of their dorsal fin.
They can be distinguished from the almost identical bald glassy (Ambassis dussumieri) by the absence of serrations on their gill covers, facial spines and interruptions of their lateral line.
Smooth glassies spend their entire lifecycles in estuaries, river mouths and floodplain lakes on the African east coast, particularly KwaZulu-Natal, Algoa Bay and Madagascar, where they form large schools. They are able to tolerate freshwater river mouths and a wide range of temperature fluctuations.
They feed on floating crustaceans and zooplankton, as well as terrestrial insects, hunting primarily during mornings and evening in the summer, and all-day during winter.