grey mullet vs haarder

grey mullet

noun
  • Any of various edible fish, of the family Mugilidae, found worldwide in coastal waters and rivers. 

haarder

noun
  • Planiliza haematocheilus, the redlip mullet, a mugilid fish. 

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