Why does Cod shrink when cooked?

Chef's answer
When fish cooks, the proteins denature or unwind, then reattach to each other.
Frequently asked Questions 🎓
The reason why fish cooks much faster than meat is because fish flesh contains less collagen that other meats such as red meats and poultry. Fish have less collagen because their muscles are used much less then compared to a cow or chicken. Because fish has less collagen, it tends to be more tender than land animals..
Does meat get more tender the longer you cook it in a slow cooker? Not if you're using a leaner cut in the slow cooker, like chicken breast or pork chops. To help keep these cuts moist, decrease the cook time to 2-4 hours.
Leaner roasts such as rump, chuck, or brisket have less fat marbling, so they can become chewy if not cooked correctly. It is the fat and connective tissue in the roast that is softened by long, slow cooking to produce flavor and tenderness.
Pork Ribs tend to be easier to cook, because they're smaller and, unlike beef ribs, you can cook both kinds in pretty much the same way..
Unlike the more lean tenderloin and chops, pork shoulder is an incredibly forgiving cut of meat. It becomes more tender as it cooks and benefits from a lengthy cook time, so even if it stays on the heat a few minutes too long, you won't suddenly end up with something dry or rubbery.
The point is super fatty and will probe tender a lot faster than the flat will. It will also take care of itself so you can just focus on the flat. You can seperate the point from the flat if you want.
You cook the bacon first because it takes longer to cook. When the bacon is almost done, you add the eggs. The leftover bacon grease is perfect for "frying" the eggs on the sheet pan.
A few more cooking questions 📍