GUDGEON (Gobio fluviatilis)  , a small fish of the Cyprinid family . It is nearly related to the barbel, and has a small barbel or fleshy appendage .at each corner of the mouth . It is the gobione of Italy, goujon of France (whence adapted in M . English as gojon), and Grassling or Grundling of Germany . Gudgeons thrive in streams and lakes, keeping to the bottom, and seldom exceeding 8 in. in length . In China and Japan there are varieties differing only slightly from the common European type .