cistern vs fish farm

cistern

noun
  • A reservoir or tank for holding water, especially for catching and holding rainwater for later use. 

  • The vessel surrounding the condenser in a steam engine. 

  • In a flush toilet, the container in which the water used for flushing is held; a toilet tank. 

  • A cisterna. 

fish farm

noun
  • A place or facility dedicated to the raising of fish or other seafood for sale. 

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