Fish can be a healthy diet choice, providing omega-3 fatty acids that lower risks of diseases like cancer, Alzheimer’s, and heart disease. However, some fish should be avoided due to high mercury levels and environmental concerns.

Mercury from industrial pollution builds up in waterways and accumulates in fish through the food chain. Large predatory fish tend to have the highest mercury levels, posing health risks like mercury poisoning.

Tilapia, popular in America, is low in beneficial omega-3s and high in inflammatory omega-6 fatty acids, which may worsen chronic diseases. Farmed tilapia from China is especially concerning.

Overfished species like Atlantic cod and flatfish (halibut, flounder, sole) face population declines, and their fishing practices often involve harmful bycatch.

Fish like Chilean bass, eel, and imported basa or catfish can be contaminated with mercury, pollutants, or harmful bacteria, so they should be limited or avoided. Imported farmed shrimp may carry pesticides and antibiotic-resistant bacteria.

High-mercury species also include shark, swordfish, king mackerel, orange roughy, and Atlantic bluefin tuna—some of which are endangered or vulnerable to extinction.

Selenium in some fish may help reduce mercury absorption, but eating high-mercury, low-selenium fish should be rare.

Better choices are wild-caught Alaskan salmon, Pacific sardines, Atlantic mackerel, and sustainably sourced cod and trout, which offer nutrients with lower environmental impact. Always check sources and labels before buying seafood.