In a tributary of the Amazon, a monster – half-man, half-fish – is captured and placed in a reservoir in a Florida national park to be observed by scientists.
John Agar
Lori Nelson
John Bromfield
Nestor Paiva
Grandon Rhodes
Dave Willock
Robert B. Williams
Charles Cane
Loretta Agar
Bill Baldwin
Jere Beery
Ricou Browning
Diane DeLaire
Mike Doyle
Clint Eastwood
Jack Gargan
Charles Gibb
Brett Halsey
Don C. Harvey
Tom Hennesy
Don House
Robert F. Hoy
Ned Le Fevre
Sydney Mason
Robert Nelson
Patricia Powers
Bert Stevens
Charles Victor
Robert Wehling
James R. Wolfe