Flesh-eating lake creatures - folklore vs. reality?

Been reading about various 'lake monsters' and cryptids associated with freshwater lakes across Europe and I'm struck by how many of them have this flesh-eating, aggressive element to the mythology. Everything from the Loch Ness Monster to more obscure Scandinavian lake creatures supposedly have stories of attacks or predatory behaviour.

Question: is there any actual evidence for large undocumented predators in lakes, or is this purely folkloric/supernatural interpretation? Because biologically, a large aquatic predator in a British or European lake seems basically impossible given food chains, oxygenation, habitat - all the actual ecological factors.

I'm not asking for cryptids to be real, I'm genuinely curious about where the line between folklore, misidentification, and actual biology sits here. Do we have any serious researchers looking at this angle?

You've basically identified the core problem with lake cryptid hunting. The 'flesh-eating monster' angle is mostly folklore and sensationalism. There's no documented large predator in any British lake that would be remotely viable ecologically. What people probably see are sturgeon, pike, or large fish creating disturbances.

The folklore angle is interesting though. A lot of aggressive lake monster myths come from genuinely dangerous situations - deep water, cold temperatures, unknown depth - that people rationalise as creature attacks. The Loch Ness mythology particularly seems built on misidentifications and human tendency to see patterns.

I'm not asking for cryptids to be real, I'm genuinely curious about where the line between folklore, misidentification, and actual biology sits here.

That's actually a really sensible framing. There's a book called 'The Great Loch Ness Monster Hoax' (I think, been a while since I read it) that goes into the scientific angles. Worth reading for the actual evidence discussion rather than just monster hunting.

Large freshwater predators do exist in some places - pike in northern lakes can be genuinely huge and aggressive. Probably explains some reports. But nothing remotely 'monster-like' in British waters. The ecosystem just wouldn't support it. Most cryptozoology of water creatures is sadly just folklore preservation rather than actual zoology.