The 5 fish that are most contaminated—and 5 you should eat instead

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From a nutritional standpoint, seafood is a pretty safe bet: It's packed with protein and good-for-you monounsaturated fats. Unfortunately, though, some types also contain mercury, which can affect a fetus or child's neurological development, says Mira Ilic, a nutritionist at the Cleveland Clinic Foundation.

Since the contaminant stays in your body for more than a year, it's crucial that you avoid ingesting it even if there's just a chance you could become a mom soon. All fish contain some mercury, but here are five types you should definitely steer clear of (along with five better alternatives).

Don't Eat: Shark

Because this fish is at the top of the food chain, it consumes other fish to survive—and oftentimes, those other fish have already been contaminated with mercury, which means sharks' levels veer into dangerously high territory.

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Eat: Wild Pacific Salmon

A four-ounce serving scores high when it comes to vitamin D, vitamin B12, selenium, omega-3 fatty acids, and flavor. All salmon sport a stellar nutritional profile, but wild Pacific salmon are considered healthier than the farmed variety. Per the EPA, you should stick to no more than 12 ounces per week if you're of childbearing age or are pregnant since all fish contain at least trace amounts of mercury.

Don't Eat: Swordfish

This tropical fish is also a top predator that feeds on other fish tainted with mercury.

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Eat: Sardines

This inexpensive option is a nutrition superstar, whether you get it fresh or in a tin. Sardines are loaded with omega-3s and are naturally high in vitamin D.

Don't Eat: King Mackerel

This voracious predator is on the do-not-eat list…unless you want to risk mercury poisoning.

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Eat: Anchovies

These teeny fish pack big flavor and are perfect in salads and pasta dishes. Besides having high omega-3 levels, anchovies are also rich in iron.

Don't Eat: Tilefish

There are many types of this fish, but the EPA makes no distinction between them and warns that women and small children should avoid any and all varieties.

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Eat: Farmed Rainbow Trout

Lake trout have a higher risk of being contaminated, but the farmed variety get a "best choice" rating from the Monterey Bay Aquarium Seafood Watch, a consumer watch group. Trout also packs lots of omega-3s and protein.

Don't Eat: Albacore Tuna or Tuna Steaks

The rules regarding tuna are tricky: Albacore tuna racks up a medium level of mercury. So if you're going to have it, the EPA advises limiting yourself to no more than one six-ounce serving per week. Same goes for tuna steak, which is also considered medium-level on the mercury scale.

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Eat: Canned Light Tuna

Awesome news if a tuna salad sandwich is your go-to lunch: This type of fish is considered low-mercury—and it's also loaded with omega-3s.