It’s no secret that seafood is a healthy source of protein, but what you may not know is that some types of seafood can be harmful to your health. In fact, there are seven types of seafood you should avoid altogether. Here’s why.

1. Imported farmed shrimp

Every day, Americans eat more than 4 pounds of shrimp. But not all of it comes from the United States, or even from the ocean. In fact, one-third is imported–and a lot of that shrimp is farm-raised in Asia on land rather than caught at sea. Imported farmed shrimp can be high in cholesterol and fat, and may contain traces of antibiotics, pesticides, and other chemicals.

2. Atlantic salmon

Atlantic salmon is one of the most popular seafood items in the United States, but it’s also one of the most dangerous. Atlantic salmon contains high levels of PCBs, or polychlorinated biphenyls, which are toxic chemicals that can cause a variety of health problems. For this reason, you should avoid eating Atlantic salmon whenever possible.

3. King crab

King crab is a type of seafood that you should avoid. It is high in cholesterol and unhealthy fats, which can lead to health problems such as heart disease. Additionally, king crab contains toxins that can be harmful to your health. If you love crab, there are many other types of seafood that you can enjoy that are much healthier for you.

4. Orange Roughy

Orange roughy is often served as sushi, but this fish’s name isn’t just a marketing ploy. It really does have an orange-like texture and flavor, which is why it got its name. Orange roughy has been around for decades, but more recently it has come under scrutiny because of some questionable sustainability issues. The fishing industry claims that orange roughy is not overfished, but some environmental groups disagree.

5. Chilean sea bass

Chilean sea bass, also known as the Patagonian toothfish, is a type of codfish that can be found in the cold waters of the Pacific and Atlantic oceans. It’s a popular seafood choice because its firm has a mild flavor, and is low in fat. However, Chilean sea bass is also high in mercury levels, which can be damaging to your health. If you’re pregnant or planning on becoming pregnant, it’s best to avoid this fish altogether.

6. Eel

Eels are a type of fish that live in the water. They can grow up to three feet long, and they usually have dark brown or black skin with light yellow spots. Eels eat other animals, like crabs, shrimp, and clams. They use their sharp teeth to break through shells and then suck out the meat inside. There are many different types of eels, but the two most common are the American eel and the European eel.

Eels are often used in sushi, and they can be found fresh or frozen in most grocery stores. If you eat sushi, make sure to ask your chef whether the eel is cooked or raw. The raw eel can contain a parasite called anisakis, which can make you very sick.

7. Swordfish

Swordfish is a type of fish that can be found in both fresh and saltwater. It is a popular choice for seafood lovers, but there are a few reasons why you should avoid it. Swordfish contain high levels of mercury, which can be harmful to your health. Additionally, swordfish are often overfished, meaning that the population is not sustainable. If you are looking for a healthier seafood option, try salmon or tuna instead.