Greentext

It needs to be really cold to form ice from salt water, due to the much lower freezing point. It does happen (look at the Arctic Circle, ice bergs, etc), but it needs to be really cold.

So the most likely places are rivers and lakes that connect to the ocean, meaning you're looking for fish that live near the coast. That basically describes sturgeon to a T, and some varieties of sturgeon live in freshwater lakes as well, hence why I guessed it. There are also freshwater varieties of many of the fish in your link.

However, the animals with crazy teeth tend to be further out in the ocean, small, or live in very deep water. Bullets also only penetrate a few feet/couple meters into the water (source):

Hiding underwater can stop bullets from hitting you.

partly confirmed

All supersonic bullets (up to .50-caliber) disintegrated in less than 3 feet (90 cm) of water, but slower velocity bullets, like pistol rounds, need up to 8 feet (2.4 m) of water to slow to non-lethal speeds. Shotgun slugs require even more depth (the exact depth couldn’t be determined because their one test broke the rig). However, as most water-bound shots are fired from an angle, less actual depth is needed to create the necessary separation.

So, we're looking for a fish that can live in fairly shallow water (3-8 ft, or 1-2.5m), live in a place where ice can form, is very large (3-ish ft diameter, or 1m diameter), and has gnarly teeth. Sturgeon fit everything except the teeth, so that's what I'm guessing it is. They're also pretty ugly and have stuff hanging off their mouth at the bottom which could be mistaken for teeth (see image here).

So yeah, my guess is sturgeon, the fish that make caviar.