The Collaborative International Dictionary of English v.0.48:

Blenny \Blen"ny\, n.; pl. Blennies. [L. blennius, blendius,
   blendea, Gr. ?, fr. ? slime, mucus.] (Zool.)
   A marine fish of the genus Blennius or family
   Blenniid[ae]; -- so called from its coating of mucus. The
   species are numerous.
   [1913 Webster]