The Cardinal Rule is don't overcook it - overcooking spoils the flavour and texture of fish. Fish is cooked as soon as it loses its translucent appearance and turns opaque (generally white) all the way through (although increasingly people are choosing to eat certain fish, such as Tuna and Salmon, rare).
High temperature
If you cook fish at 175°C or more, you get an uneven result. The outside of the fish is done more quickly than the middle. And the heat continues to spread inwards into the flesh long after you have removed the fish from the heat.
A medium heat should be used when grilling fish, whole or pieces. Using too high of a heat will cause some parts to cook too quickly and dry out while other parts will not be done all the way through.
As most fish are ectotherms, their physiology is strongly affected by temperature. Temperature affects their metabolic rate and thus their energy balance and behavior, including locomotor and feeding behavior.
Fish that seems tough when you bite into it is probably overcooked. As it moves from done to "overdone," the flesh continues to firm then shrinks, pushing out moisture, which evaporates and leaves the fish dry and chewy. Fresh fish needs little embellishment, for its flavor is as fragile as its flesh.
In addition to the chalky mouthfeel, oftentimes overcooked salmon will also develop bits of opaque white goop on top. This is just protein, or coagulated albumin, and is completely safe to eat (or scrape off with a fork), but is it appetizing? Not so much.
Unlike meat, fish and shellfish do not need to be "tenderized" by cooking. In fact, overcooking toughens seafood and makes it dry out because its natural juices are lost. Remember, if your immune system is compromised in any way (see above), it is important to cook all seafood and protein-based foods.
Thermal stress is a term to describe a temperature change that is severe enough to cause unfavorable and even lethal conditions to aquatic organisms, their populations, community structure, or ecosystem. Aquatic organisms have evolved to function most efficiently within an optimal range of water temperature.
Viewed from a high-level perspective, as meat is heated the components that make it up change. These changes result in structural transformations that affect the texture, juiciness, and mouthfeel of the meat. The higher the temperature of the heat applied to the meat, the faster these changes happen.
Most aquarium fish can withstand temperatures up to 80°F for a short period of time, though it may cause complications to develop. At higher temperatures, aquarium fish require more food because their metabolisms have to work that much harder.
Heat oven to 450°F. Spray a baking sheet or shallow baking dish with nonstick cooking spray. Place fish on baking sheet in a single layer, season as desired. Bake uncovered, 10 minutes per inch of thickness or until fish is done.
So how hot is too hot? Coldwater fish such as trout, steelhead and salmon will start to feel stressed when water temperatures hit 68°F. Warmwater fish can tolerate temperatures up to 86°F, but they'll probably be sluggish and slow to bite.
Signs of stressed fish during hot weather
Rapid gill movement or gasping for air at the surface or at the bottom of the tank are the main signs of stress during hot weather. Algae growth may increase, and the water may begin to turn cloudy due to a bloom of heterotrophic bacteria.
Fishes probably died because they were unable to obtain the additional oxygen required for metabolism at higher temperatures. Repeated die-off events over the last 130 years indicate that some fishes have not yet adapted to rises in seawater temperature.
You'll need a deep-fry or candy thermometer. Bring the heat up slowly until the oil is between 350 and 375 degrees F — too low and you'll get greasy food, too high and it'll burn.
Cooking food at high temperatures changes its chemical structure, producing toxic products called NFCs, such as trans-fatty acids (TFAs) and advanced glycation end-products (AGEs).
During heating, the different meat proteins denature as described above and they cause meat structural changes, such as the destruction of cell membranes (Rowe, 1989), transversal and longitudinal shrinkage of meat fibres, the aggregation and gel formation of sarcoplasmic proteins and the shrinkage and the ...
During the heating process or the “cooking” of food, a complex series of physical and chemical changes take place. These changes vary according to the heating method and time exposed, but may ultimately include changes in nutrient composition, fat content, moisture, flavor, smell, texture, and color.
Strange Swimming: When fish are stressed, they often develop odd swimming patterns. If your fish is swimming frantically without going anywhere, crashing at the bottom of his tank, rubbing himself on gravel or rocks, or locking his fins at his side, he may be experiencing significant stress.
Heat Stress. Workers who are exposed to extreme heat or work in hot environments may be at risk of heat stress. Exposure to extreme heat can result in occupational illnesses and injuries. Heat stress can result in heat stroke, heat exhaustion, heat cramps, or heat rashes.
Overcooking is the most common mistake most people make when they cook fish. It's also the worst, since fish that's left in the pan too long turns tough, dry, and tasteless. Cook times vary for different types of fish, but in general, you want to stay in the range of 3 to 5 minutes per side.
Beware the temptation to overcook… that lovely fillet of halibut can become tough and dry faster than you think. Always err on the side of undercooking your fish; as a matter of fact most people enjoy fish that is still a little translucent in the center.
Many types of fish are delicate and tender, so you want to avoid overcooking them. The best way to tell if your fish is done is by testing it with a fork at an angle, at the thickest point, and twist gently. The fish will flake easily when it's done and it will lose its translucent or raw appearance.