You don’t get the grill or stove warm enough
The pan or grill should be searing hot. When cold fish proteins come in contact with hot metal, they form chemical bonds that are extremely tough to break. It’s why you end up leaving part of the fish behind when you flip it. If you’re cooking your fish on the grill or stovetop, be patient. “Put your pan on the stove and turn the burner on medium heat for three to five minutes before placing your fish,” says Giuseppe Tentori, executive chef and partner at GT Fish & Oyster, a seafood restaurant in Chicago. When the pan or grates are extremely hot, the fish is easier to flip.