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
Brett Halsey
Pete (uncredited)
Nestor Paiva
Captain Lucas
Bert Stevens
Search Party Member (uncredited)
Bill Baldwin
Patrol Boat Dispatcher (voice / uncredited)
Lori Nelson
Helen Dobson
Robert B. Williams
George Johnson
Dave Willock
Lou Gibson
Charles Cane
Police Captain
Robert F. Hoy
Charlie (uncredited)
Don C. Harvey
Mac - Spotlight Party Leader (uncredited)
Grandon Rhodes
Jackson Foster
Diane DeLaire
Miss Abbott (uncredited)
John Bromfield
Joe Hayes
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)