First and foremost, know your fishmonger. If you trust the store where you purchase fish, you should never have to worry about freshness.
However, here are some tips to tell whether whole fish is fresh. It should have a clear eye. A cloudy or sunken eye means the fish is past its best-before date. If you press the fish with your finger, the flesh should jump back. If it feels spongy, sideline it. The underside of the gills should be bright red or pink. If brownish, the fish has been out of the water for too long. Fish should always smell fresh. It should never have a fishy odour and it should glisten as though it is just out of the water.
It is harder to tell the freshness of fish fillets, but they should be translucent, firm to the touch and have no odour.
To store, remove any plastic packaging and place the fish in a dish, covered with a paper towel. Place it at the back of your refrigerator, which is colder, and keep for no more than two days. If you need to preserve the fish for longer, rub it with yogurt or soy sauce – it will last another day.
When it comes to grilling fish, it’s preferable to use either whole fish with the bone or thick fillets, such as salmon, halibut or sea bass. Thin fillets dry out, burn easily and are next to impossible to get off the grill.
Preheat the grill to high, making sure it’s superclean to prevent the fish from sticking. Always grill fish with the lid down, and don’t wrap it in foil, because it will steam, robbing it of any grilled taste.
An oiled grilling basket is a godsend because it allows you to easily turn the fish. If you don’t have one, fill a spray bottle with oil and spray both the grill and the fish.
For whole fish, make a few slashes in the skin to keep the fish from curling up. Grill turning once with two wide spatulas, until the eye turns white and the flesh near the bone is slightly pink. I like to douse fish with a little extra virgin olive oil, lemon juice and lots of herbs before serving. Some chefs place vegetables, such as fennel or even lemon slices, under whole fish to prevent sticking. These make an attractive garnish as well.
Fillets should go flesh side down until they are browned and turn easily, about 2 to 3 minutes. Flip and grill on the skin side until the fish is opaque. If the fish sticks, give it another minute. It will release when it is ready. Fish fillets and whole fish cook about 8 minutes per inch of thickness, or until an instant-read thermometer inserted in the centre of the flesh reaches 125 F for slightly rare in the middle. If you want to fully cook, the temp should reach 145 F, but because it continues to cook after leaving the grill, beware of ending up with an overcooked fish.