How Long Should You Marinate Fish?

If you want fish to retain seasoning while cooking, marinate it first. But for how long? Marinating time rules dictate fish should marinate for 30 minutes to an hour. But the exact time needed for marinating fish actually varies depending on the kind of fish and marinade you're working with. Fish is more fragile than a big hunk of chicken or beef, so you actually shouldn't be leaving it to soak in a marinade for super long periods of time. Otherwise, your fish might end up unpleasantly squishy.

For thicker fish cuts like tuna or swordfish steaks — thick, bone-in pieces of fish cut from the top fin to the bottom fin — marinate between one and two hours. For fillets, the most common fish cut that comes from a fish's side, keep the time down to an hour or less. The type of fish fillet can matter, too. Soak firmer fish fillets, like salmon or halibut, for up to an hour and flakier fish, like cod, for 15 to 30 minutes. 

As for marinades, if it is highly acidic (containing lots of vinegar or citrus juices, for example) err on the side of caution and stick to 20 minutes or less. If you marinate fish in acidic liquid for too long, the acid can alter the texture and taste for the worse.

First things first — choose the right container for marinating. Ziploc bags work if you don't want any clean-up, but you can use glass or ceramic bowls. If you are using a lid-less bowl, make sure to seal it with something like plastic wrap. Just don't use aluminum foil while marinating, as the acidity of your marinade may break down the foil. Once you've sealed your marinating fish, stick it in the fridge and set a timer. You don't want your meal to go to waste because you forgot and discovered it when the fish developed a less-than-desirable texture.

Acidic ingredients are worth using in a marinade, adding flavor and helping said flavor sink deeper into the fish's flesh. Oil is also a flavor vehicle (great for marinating salmon for the crispiest possible fish), though you'll want to be careful about what oil you use if you're grilling your fish. A high-smoke-point oil like peanut or canola oil is best in that case. These two ingredients (fat and acid), plus salt and some spices, herbs, and other flavorings, are all you'll need for a flavorful marinade.

That said, while the marinade might taste good, discard any marinade the raw fish was soaking in. If you're making a sauce, make sure to portion out some of the marinade before combining it with your raw fish. Or, if you want to make full use of the marinade, boil it for no less than three minutes after you remove the fish.