black cod vs gempylid

black cod

noun
  • Synonym of sablefish (Anoplopoma fimbria); (the sablefish is not a species of codfish; but is referred to as cod informally) 

gempylid

noun
  • Any fish of the escolar family, Gempylidae. 

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