When you're preparing a nice fish dinner, the 10-minute rule can help you estimate how long your piece of fish needs to be cooked. If you think your fish is ready, this simple fork test can let you know for sure.
Photo by thebittenword.com.
If you have an instant-read or meat thermometer, the center of your fish should reach approximately 65 degrees Celsius. Christine Gallary at The Kitchen suggests, however, that you can also check the fish with a fork:
Another easy way to tell without even using a thermometer is cutting the piece of fish in the thickest part and looking at the texture. The fish should be opaque (not translucent like when it's raw) and break easily into flakes when you nudge it with a fork.
If the meat is still translucent and it doesn't flake, it needs more time. Fish can be a tricky protein to cook with, but simple tricks like these can make a huge difference.
The Right Internal Temperature for Cooked Fish [The Kitchn]