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.
Directed by
Jack Arnold
Clint Eastwood
Jennings (uncredited)
John Agar
Prof. Clete Ferguson
Robert B. Williams
George Johnson
Dave Willock
Lou Gibson
Brett Halsey
Pete (uncredited)
Bert Stevens
Search Party Member (uncredited)
Don C. Harvey
Mac - Spotlight Party Leader (uncredited)
Lori Nelson
Helen Dobson
Charles Cane
Police Captain
Grandon Rhodes
Jackson Foster
Bill Baldwin
Patrol Boat Dispatcher (voice / uncredited)
Nestor Paiva
Captain Lucas
John Bromfield
Joe Hayes
Robert F. Hoy
Charlie (uncredited)
Diane DeLaire
Miss Abbott (uncredited)
Loretta Agar
Woman on Boat (uncredited)
Jere Beery
Photographer (uncredited)
Ricou Browning
The Gill Man (in water) / Lab Technician (uncredited)
Mike Doyle
Cop (uncredited)
Jack Gargan
Skipper (uncredited)
Charles Gibb
Cop (uncredited)
Tom Hennesy
The Gill Man (on land) / Marineland Diver (uncredited)