Actually, it seems cold conditions make animals more likely to grow big in order to be more energy efficient. That is why lots of deep sea creatures are larger than their counterparts that live on the warmer waters near the surface.
Jacob Gellar's video on this is excellent... is a sentence you can say about many subjects. Anyway he highlights how the open ocean is kinda like deep space with zero visibility. Any square mile of open ocean is several cubic miles of water. Animals the size of cruise ships disappear at that scale.
23 miles is pretty fucking big for a lake. Just reading the Wikipedia on it shows what a dumb criticism your comment is:
At 56 km2 (22 sq mi), Loch Ness is the second-largest Scottish loch by surface area after Loch Lomond, but due to its great depth it is the largest by volume in Great Britain. Its deepest point is 230 metres (126 fathoms; 755 feet), making it the second deepest loch in Scotland after Loch Morar. It contains more water than all the lakes in England and Wales combined, and is the largest body of water in the Great Glen, which runs from Inverness in the north to Fort William in the south.
Lake Superior is one of the largest lakes one the planet. That's a stupid standard to hold lakes to. It's like saying Chicago isn't a big city because it's smaller than Tokyo.
If you're trying to refute an idiotic theory it helps to not sound like an idiot yourself.
You understand that fish breed, right? That all the food that any of us will ever need for generations to come does not currently exist in the here and now?
Fish breed but Nessie fucks around for hundreds of years without a single shit washing ashore or a decent photo. In fact we live in a world of cameras, my phone has 5 of them right now, any of which would do just fine.