The Gemara (Avodah Zarah 40a) mentions that if you find a "kilbis" (כילבית) fish in fish brine you can eat it. What does a "kilbis" fish translate out to in English?
Jastrow suggests that the kilbith fish may be a stickleback.
כִּלְ' , (כִּילְבִּית) כִּילְכִּית f. (=כילכלית, v. כלכל; or denom. of כלב, emp. כּוּלָב) name of a small fish, supposed to be a stickleback.
Dictionary of Targumim, Talmud and Midrashic Literature by Marcus Jastrow, 1926
The kalbith was a kind of stickleback which was supposed to breed only in brine formed with the clean species of fish.
Thank you, Tamir Evan, for finding this.
It seems that the kilbith's exact identity is uncertain.