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Siamese fighting fish

noun
  1. a labyrinth fish, Betta splendens, that has been bred for centuries to develop brilliant coloration, very long fins, and pugnacity.

Origin of Siamese fighting fish

First recorded in 1930–35
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for siamese fighting fish

Siamese fighting fish

noun
  1. a brightly coloured labyrinth fish, Betta splendens, of Thailand and Malaysia, having large sail-like fins: the males are very pugnacious
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012