miller's thumb

/ˈmɪlərz ˌθʌm/
noun
  1. A small freshwater fish with a broad, flat head, also called a bullhead or sculpin.
    • The miller's-thumb hides under rocks in fast-flowing rivers.
    • Local fishermen call the small, flat-headed fish a miller's-thumb.
    • We caught a miller's-thumb in the stream and released it back into the water.
Synonyms
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