The Collaborative International Dictionary of English v.0.48:

Grindle \Grin"dle\, n. (Zool.)
   The bowfin; -- called also Johnny Grindle. [Local, U. S.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Bowfin \Bow"fin`\, n. (Zool.)
   A voracious ganoid fish (Amia calva) found in the fresh
   waters of the United States; the mudfish; -- called also
   Johnny Grindle, and dogfish.
   [1913 Webster]