threespine stickleback

or three-spined stick·le·back

[three-spahyn stik-uh l-bak or three-spahynd stik-uh l-bak]
noun
  1. a widely distributed stickleback, Gasterosteus aculeatus, occurring in marine, brackish, or fresh waters throughout the northern hemisphere.

Origin of threespine stickleback

First recorded in 1890–95
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018