The Truth About “Mercury in Fish” Charts — Why Context Matters

Every so often, a well-meaning “mercury in fish” chart or infographic makes the rounds online. It looks neat, official, and easy to understand — a simple list of which fish you “should” or “shouldn’t” eat.

But as someone deeply involved in the seafood industry, I have to say it: these charts, while well-intentioned, are often misleading and incomplete.

At Greenfish, we believe in empowering our customers with facts — not fear. So let’s unpack this properly.

Not All Fish Are Created Equal

Mercury occurs naturally in the environment, and nearly all fish contain trace amounts. The key factor isn’t the species name on a poster — it’s the fish’s lifespan, location, size, and diet.

Fish that live longer and grow larger, like Northern Bluefin Tuna and Sharks, accumulate higher levels of mercury over time. These apex predators can live for 40 to 50 years, feeding on smaller fish throughout their lives — so their mercury levels naturally build up.

On the other hand, short-lived, fast-growing fish like Dorado, Yellowtail, and Cape Salmon contain much lower mercury levels. They live shorter lives, feed lower down the food chain, and are caught far younger — meaning less time for mercury accumulation.

Yet many of these species are still listed as “moderate” or “avoid” on generic charts, simply because they share a name with distant relatives found in different oceans under completely different conditions.

Location and Method Matter

Another big missing piece from these posters is where and how the fish was caught.

At Greenfish, our fish are caught in clean, cold Atlantic waters off the Cape coast, using low-impact handline methods that target specific species — not vast nets that haul up everything in their path.

These practices, combined with local regulations and strict handling standards, mean that the fish we bring to your table are as clean, sustainable, and safe as possible.

Why You Can Trust Your Local Catch

When you buy from a trusted, transparent supplier like Greenfish, you’re not just getting a label — you’re getting a story.

We know who caught your fish, where it was caught, and how it was handled.

We don’t deal in mystery species or mass imports from unknown waters.

We deal in traceable, responsibly harvested, low-impact seafood, the way nature intended.

So yes — be aware of mercury, but don’t be alarmed, At Greenfish as part of our food safety protocol we have been taking random samples of our fish for almost 2 decades, testing for mercury, histamine, Staphylococcus, E.coli, Listeria, TCV (total colony count) surface swabs and Hand Swabs.

A chart on the internet will never replace the real-world context that comes from responsible fishing, scientific understanding, and local knowledge.

Fish is one of the most nutrient-dense, heart-healthy proteins on the planet. Avoiding it altogether because of an oversimplified poster would be like avoiding fruit because someone once said “sugar is bad.”

The truth is more nuanced.

The ocean — like life — deserves a little more context.

Eat smart. Eat local. Eat with confidence.