blackfish vs rockperch

blackfish

verb
  • To go fishing for blackfish. 

  • To adopt signifiers of black identity (for example, by darkening the skin, or wearing traditionally black hairstyles). 

noun
  • The Atlantic salmon, Salmo salar, especially a female after spawning. 

  • Any of various dark-coloured fish of the Old World, especially the rudderfish (Centrolophus niger). 

  • A pilot whale, genus Globicephalus (occasionally also used for various other whales). 

  • Any of various dark-coloured fishes of Australasia, especially the luderick, Girella tricuspidata, and a freshwater fish, Gadopsis marmoratus. 

  • Either of two dark-coloured fish of the west Atlantic, the tautog of New England (Tautoga onitis) and the black sea bass (Centropristis striata). 

rockperch

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