characin
Concise Oxford English Dictionary © 2008 Oxford University Press:
characin /ˈkarəsɪn/
▶noun a small freshwater fish of a tropical family (Characidae ) including the piranhas and tetras.
– origin C19: from mod. L. Characinus (genus name), from Gk kharax ‘pointed stake’.
'characin' also found in these Oxford entries:

