coalfish vs gempylid

coalfish

noun
  • any of several blackish fish, especially Pollachius virens, a pollack, and Anoplopoma fimbria, sablefish. 

gempylid

noun
  • Any fish of the escolar family, Gempylidae. 

How often have the words coalfish and gempylid occurred in a corpus of books? (source: Google Ngram Viewer )