Anas is a genus of dabbling ducks. It includes the pintails, most teals, and the mallard and its close relatives. The name Anas is the Latin for "duck".

1/ The Eurasian teal (Mòng két, Anas crecca), common teal, or Eurasian green-winged teal
The bird gives its name to the blue-green colour teal.
2/ Mallard or wild duck (Vịt cổ xanh, Anas platyrhynchos) 

3/ Pintail or northern pintail (Vịt mốc, Anas acuta) 
The epithet acuta comes from the verb acuere meaning "to sharpen" which refers to the pointed tail of the male in breeding plumage.

4/ Indian spot-billed duck (Vịt trời, Vịt mỏ đốm, Anas poecilorhyncha) 
The English name is derived from the red spot at the base of the bill that is found in the mainland Indian population.
The specific epithet poecilorhyncha combines the classical Greek words poikilos meaning "pied" or "spotted" and rhunkhos meaning a "bill".