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