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.
as Prof. Clete Ferguson
as Helen Dobson
as Joe Hayes
as Captain Lucas
as Jackson Foster
as Lou Gibson
as George Johnson
as Police Captain
as Woman on Boat (uncredited)
as Patrol Boat Dispatcher (voice / uncredited)
as Photographer (uncredited)
as The Gill Man (in water) / Lab Technician (uncredited)
as Miss Abbott (uncredited)
as Cop (uncredited)
as Jennings (uncredited)
as Skipper (uncredited)
as Cop (uncredited)
as Pete (uncredited)
as Mac - Spotlight Party Leader (uncredited)
as The Gill Man (on land) / Marineland Diver (uncredited)
as Diver (uncredited)
as Charlie (uncredited)
as Newscaster (uncredited)
as Police Announcer (uncredited)
as Dr. McCuller (uncredited)
as Girl in Convertible
as Search Party Member (uncredited)
as Policeman (uncredited)
as Joe (uncredited)
as Man at Tank (uncredited)
