Fish is super lean so high heat short time is the rule. I try to cook it so it finishes at rest. You also only want to flip once ever for the entire cooking and handling process. So cook presentation side down first and finish on skin side. Oysters and clams when properly cleaned just require timing. Need to be pulled as soon as they open to have good texture. Fish stock, fumet, is easy. Just needs to be made fresh and not overcooked. Overcooking will ruin it. Biggest mistake people make with fish/seafood is too much cooking usually. Seafood in general is high heat, short time, cook just enough and mo more. Also don’t skimp on the cooking fat.