Check the eyes of whole fish - they should be clear and bulging, not cloudy or sunken.
Smell the seafood - it should have a fresh, oceanic scent, not a strong fishy odor.
Inspect the flesh - it should be firm and spring back when touched, not mushy or slimy.
Look for bright, shiny skin on fish and shellfish - dull or discolored skin can indicate age or poor handling.
Check for ice crystals or frost on frozen seafood - this can indicate that it has been thawed and refrozen, which can affect quality and safety.
Buy from a reputable source and pay attention to sell-by dates - seafood should be consumed within a day or two of purchase for optimal freshness and safety.