10 types of fish you may want to avoid eating

Not every fish you catch or see at the market is worth putting on a plate. Some carry higher levels of contaminants, others are prone to spoilage, and a few simply come with risks that outweigh the reward. Experience on the water—and at the cleaning table—teaches you that not all fillets are created equal.

This isn’t about fear, and it’s not about avoiding fish altogether. It’s about knowing what you’re dealing with before you cook it. The following fish have earned a reputation among anglers and outdoorsmen for reasons that deserve your attention before the next meal.

King Mackerel

King mackerel are strong fighters and impressive fish, but they carry a well-documented mercury issue, especially in larger specimens. The bigger the fish, the more time it’s had to accumulate contaminants, and that shows up on your plate.

You might be fine with an occasional meal, but regular consumption isn’t a good idea. Many experienced anglers will keep smaller kings and release the big ones for this reason. It’s not about taste—properly prepared, they’re decent—it’s about what builds up in the meat over time.

Tilefish

Tilefish live deep, and that deep-water habitat plays a role in their contamination levels. They’re known for carrying some of the highest mercury concentrations found in commonly harvested fish.

Even though they’re marketed as a premium seafood option, you’ll want to think twice before eating them regularly. Occasional consumption might not be an issue, but this isn’t a fish you want in heavy rotation. Most seasoned fishermen avoid keeping them for the table unless they’re making a rare exception.

Orange Roughy

Orange roughy has been popular in restaurants for years, but there’s a catch—it lives a long time. Some of these fish can live well over a century, which gives them plenty of time to accumulate toxins.

That long lifespan translates directly to higher mercury levels. On top of that, their slow reproduction rate raises sustainability concerns. It might look like a harmless white fish fillet, but there’s more going on beneath the surface than most people realize.

Shark

Shark meat shows up in different forms, but it comes with a couple of issues you shouldn’t ignore. First, like other large predators, sharks carry high mercury levels. Second, the meat can contain compounds that break down into ammonia if not handled properly.

If you’ve ever had shark that tasted off, that’s usually why. Even when prepared correctly, it’s not a fish most experienced anglers prioritize for eating. There are better, cleaner options that don’t come with the same baggage.

Swordfish

Swordfish is another big-game favorite that ends up on dinner plates, but it’s firmly in the high-mercury category. Size and diet both work against it, especially for those who eat fish frequently.

You can still enjoy it occasionally, but it’s not something to treat as a regular protein source. Many anglers who chase swordfish don’t even keep them for the table, knowing there are better choices with fewer long-term concerns.

Escolar

Escolar has a reputation that spreads quickly among people who’ve tried it. The fish contains indigestible wax esters that your body can’t break down properly.

The result isn’t subtle. People often experience digestive issues after eating it, sometimes severe enough to swear it off permanently. It’s occasionally mislabeled in markets, so knowing what you’re buying matters. Once you’ve had a bad experience with escolar, you won’t forget it.

Bluefin Tuna (Large Specimens)

Bluefin tuna is prized worldwide, but larger individuals carry significant mercury loads. Like other apex predators, they accumulate toxins over time, especially in open-ocean environments.

You’re not dealing with the same risk in smaller tuna species or younger fish. But when it comes to big bluefin, moderation matters. Many seasoned fishermen will enjoy it sparingly rather than making it a staple.

Farmed Salmon (Poorly Managed Sources)

Not all farmed salmon is equal. In poorly managed operations, fish can be exposed to crowded conditions, lower-quality feed, and higher contaminant levels.

That doesn’t mean all farmed salmon is bad, but you need to know the source. Experienced anglers and buyers often look for wild-caught options or verified farms with better practices. Without that, you’re taking a gamble on quality and long-term safety.

Channel Catfish from Polluted Waters

Channel catfish are a staple in many parts of the country, and when they come from clean water, they’re excellent eating. The problem shows up when they’re pulled from polluted rivers or reservoirs.

Catfish are bottom feeders, which means they pick up contaminants from their environment. If the water isn’t clean, neither is the fish. Knowing your water source matters more with catfish than almost anything else you’ll catch.

Barracuda

Barracuda are aggressive predators, and that diet works against them when it comes to eating. In certain regions, especially tropical waters, they’re known carriers of ciguatera toxin.

This toxin doesn’t cook out, freeze out, or disappear with preparation. If it’s in the fish, it’s in the meat. Experienced anglers in affected areas often avoid eating barracuda altogether, even if they enjoy catching them. It’s one of those risks that simply isn’t worth it.