Killer Fish Films Jaws (1975)
The Shallows (2016)
Lake Placid (1999)
Deep Blue Sea (1999)
The Meg (2018)
Piranha 3DD (2012)*
Rogue (2007)
Crocodile (2000)
Much as i like
Humanoids From the Deep and
Creature from the Black Lagoon,
Reptillicus and so on, they aren't killer fish movies. They are all man made horrors / monsters, so to speak rather than something real living beneath the surface.
Unless you really think there are
Humanoids from the Deep. In which case i'd get help.