roughy vs slimehead

roughy

noun
  • Any of several marine fish of the related genus Trachichthys, which have rough and spiny scales. 

  • The orange roughy, Hoplostethus atlanticus. 

slimehead

noun
  • Any of the long-lived deep-sea fish forming the family Trachichthyidae. 

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