->''"Sargassum -- the weed of deceit."''\\
''"Sargassum fish -- mighty hunter of the deep. What an inspiration you have been in my plot."''

''The Blood Waters of Dr. Z'', also known as ''Zaat'', is a 1971 film about Dr. Leopold, a mad scientist who wants to get revenge on all those who thought he was silly for wanting to make a half-man, half fish. Using a chemical of his creation (the titular "[=ZaAt=]"), he makes himself into his first test subject, and turns the local catfish huge and man-eating. Next steps: kill those who wronged him, and find a mate to breed the new race, and then [[TakeOverTheWorld conquer the universe]].

Shot on location in, of course, [[OnlyInFlorida Florida]].

For the ''Series/MysteryScienceTheater3000'' version, please go to the [[Recap/MysteryScienceTheater3000S10E05TheBloodWatersOfDrZ episode recap page]]. WebVideo/RedLetterMedia [[http://redlettermedia.com/half-in-the-bag-zaat/ reviewed]] it as well, as did New York Daily News' Phantom of the Movies, a decade later in 1984. (It took that long for the film to reach the Times Square grindhouse theaters.)
!!Tropes present in ''The Blood Waters of Dr. Z'' include:

* AliensInCardiff: The world is threatened by a mutant in Green Cove Springs, Silver Springs and Switzerland (no, not ''[[UsefulNotes/{{Switzerland}} that]]'' [[UsefulNotes/{{Switzerland}} one]]), all towns in Florida.
* TheBadGuyWins: ...Sort of. It's probably more accurate to say The Bad Guy Manages To Pull A No Score Draw.
** If getting the canisters to the ocean will mutate all sea-life then he did indeed succeed. We don't know if the bullets killed him, and also he got the girl... kind of.
* BlessedWithSuck: Being turned into a fish probably wasn't worth the constant, wracking agony.
* DeepSouth: Especially the Sheriff.
* {{Fainting}}: Near the end, the female scientist faints when Dr. Leopold breaks into the cabin where they've set up shop. She then stays unconscious as he roughly carries her, over his shoulder through a humid, noisy, treacherous swamp, for ''several miles''.
* GainaxEnding:
--> '''Servo''': This film was the winner of Canne's Palme de Huh? award.
* HeroicBSOD: Martha gets kidnapped by the mad doctor, gets injected by the formula, narrowly avoids getting transformed into a fish-woman, and then afterwards she's not quite the same--zombielike, she follows the doctor into the ocean at the end.
* LeaveTheCameraRunning: [[Series/MysteryScienceTheater3000 MST3K]] fans were lucky in that the televised version used for the show cut the first 15-20 minutes, which was nothing but Dr. Leopold ''walking around'', ''checking equipment'', and ''reading notes'', and ''nothing else''.
* LyricalDissonance: "I'm planning revenge on your friends..."
* NoEnding: The movie just... ends ambiguously.
* NobleBigotWithABadge: The Sheriff. His assistant Ben sees him as a fatherly figure, so it could be an affectation rather than any real racism.
** He also calls a white photographer "boy", so he may just be an InnocentBigot.
* NonIndicativeName: There is no Dr. Z. It could have been a mistaken case of the distributor thinking "[=ZaAt=]" was Dr. Leopard's name.
* NotableOriginalMusic: [[http://www.youtube.com/watch?v=XRCMxodXrQo "World War II]] Boy" by Jamie [=DeFrates=]. If you interpret the mildly incoherent lyrics to the ''World War II Boy'' to being in reference to Dr. Leopold, then it counts as his VillainSong, but with a rather upbeat, catchy tune.
-->''Hey World War II boy
-->Holding back a wagging fatter
-->Olaf messing with your luck
-->Keeps you up at night
-->Mel Pool hang a cocoa bean
-->Drags you down helplessly step of fate
-->Tombstones are piling up your last mistake
-->We all wait for you to give us a break
-->Give us a break!
-->Sashay through the sarcasm [sic]
-->Stalking, skulking through the sargassum
-->Sashay through the sargassum
-->Planning re-veenge on your friends!''
* RoaringRampageOfRevenge: Two of Leopold's victims are men who denied him permission to do his unethical experiments.
* RoomFullOfCrazy: Dr. Leopold's huge chart showing each phase of the years he spent on his EvilPlan to turn himself into a half-catfish hybrid.
* ScheduleFanatic: Say what you want about Doctor Leopold, he's meticulous and has EVERYTHING planned out on a huge chart on his wall. Almost makes you believe that he could conquer the universe through transforming himself into a fish. ''Almost''. Can't stress that enough. ([[DownerEnding Or did he?]])
* SoundtrackDissonance: ''World War II Boy'' sung over the beginning which is upbeat and catchy in contrast to the doughy, unimpressive evil scientist.
* TakeOverTheWorld: Through mutated walking catfish no less.
* TheyCalledMeMad: "They think I'm insane... they're the ones who are insane!"
* ThoseWackyNazis: Leopold is an ex-Nazi, despite being obviously too young for it.
* TodayXTomorrowTheWorld: Emphasized when Catfish!Leopold emphatically marks Florida with an "X" after infecting the water.
* TranshumanTreachery: Well, strictly speaking he was plotting against humanity before becoming transhuman.
* WhosLaughingNow