Fish is often praised as one of the healthiest foods on the planet, packed with protein, omega-3 fatty acids, and vital vitamins. Yet, not every part of a fish is safe to consume. Hidden toxins and harmful substances can lurk in certain organs, and eating them could do more harm than good.

Surprisingly, some parts people believe are “nourishing” can actually be toxic—causing digestive distress, organ damage, or worse. Here are five fish parts you should absolutely avoid if you want your meal to stay both delicious and safe.

1. Fish Gallbladder – Dangerous Despite the “Health Tonic” Myth

Among all fish organs, the gallbladder is the most dangerous. Some traditional beliefs suggest drinking fish bile can strengthen the body or improve vitality, but science shows the opposite.

Fish bile contains potent toxins that attack the nervous system, liver, and kidneys. Even a small amount can trigger severe nausea, vomiting, diarrhea, and abdominal pain. In more serious cases, it can cause seizures, acute kidney failure, liver damage, or even death.

Every year, hospitals report cases of poisoning linked to the mistaken practice of consuming fish bile as a “supplement.” This is a deadly myth that should be avoided at all costs.

2. Fish Gills – A Breeding Ground for Bacteria and Parasites

Gills act as the respiratory filter for fish, constantly in contact with the water around them. This makes them a natural trap for dirt, parasites, and bacteria.

Eating gills essentially means introducing a large amount of microorganisms directly into the body. The risk is particularly high if the fish came from polluted water sources, where harmful parasites and pathogens thrive. Consuming gills can easily lead to digestive problems, food poisoning, and in severe cases, parasitic infections. For this reason, professional chefs always discard gills during preparation.

3. Fish Intestines – Loaded with Waste and Toxins

Just like in humans, fish intestines are responsible for breaking down food. That also means they are full of waste residue, undigested material, and harmful microorganisms.

Unless meticulously cleaned, intestines can harbor dangerous bacteria that may cause foodborne illness. In fish raised in contaminated ponds or polluted rivers, the intestines may also accumulate heavy metals and other toxic substances. Eating them could lead to long-term health issues. The safest approach is to remove them completely before cooking.

4. Fish Brain – High in Cholesterol and Toxic Risk

Some people eat fish brain under the assumption it helps “nourish the brain.” Unfortunately, that’s more myth than fact. Fish brain is high in unhealthy cholesterol, which, when consumed in large amounts, can contribute to elevated blood lipids and cardiovascular problems.

Even more concerning, in farmed fish, the brain may concentrate chemical residues, antibiotics, or toxins from their feed and environment. Instead of boosting your brain health, eating fish brain could be quietly harming your body. Moderation—or better yet, avoidance—is the best choice.

5. The Black Membrane Inside the Fish Belly – A Hidden Toxic Layer

When you open up a fish, you’ll often find a thin black layer clinging to the belly cavity. This is the peritoneal membrane, and it contains lipofuscin, a pigment that tends to accumulate toxins and waste byproducts.

Not only does it add a strong fishy odor to the dish, but eating it can irritate digestion and, over time, put strain on the liver. That’s why experienced cooks always scrape this layer away before preparing fish. Doing so not only makes the dish taste fresher but also protects your health.

How to Enjoy Fish Safely and Reap Its Health Benefits

Fish is undeniably a powerhouse of nutrition, but the key lies in careful selection and preparation:

• Always remove the five risky parts: gallbladder, gills, intestines, brain, and the black belly membrane.
• Choose fresh fish with clear eyes, shiny scales, firm flesh, and no unusual odor.
• Cook thoroughly to kill bacteria and parasites—avoid undercooked or raw fish from questionable sources.
• Rotate fish types (river fish, sea fish, farmed fish) to reduce the risk of heavy metal buildup.
• Store properly by refrigerating or freezing; ideally, cook fish the same day you buy it.

The Bottom Line

Fish remains one of nature’s best superfoods—but only when handled the right way. By eliminating these five dangerous parts, you can enjoy fish that is not only flavorful but also safe for the whole family.

Next time you prepare fish, remember: safety starts with what you throw away, not just what you eat.