Fish is an indispensable food for humans. Scientists have indicated that there are five types of fish commonly found in traditional markets that are highly contaminated with heavy metals and parasites, and even fish sellers avoid consuming them.
1. Catfish
Catfish are highly adaptable, disease-resistant, and belong to a scavenger species with unusual eating habits. They can survive in extremely dirty environments, such as foul-smelling sewers or manure pits, and will consume almost anything.
In some farming facilities, catfish are raised in ponds beneath poultry enclosures to maximize feed efficiency. As a result, they are exposed to various parasites that accumulate in their bodies.

2. Eel
Eel is known for its ability to regulate blood sugar levels and promote brain health. It has a unique, large bone along its back, and its meat is highly prized for its flavor.
While eels are naturally found in a variety of habitats, the current water quality in many places is questionable. High levels of toxins and pollutants make wild eels unsuitable for consumption, according to experts.
3. Silver Carp
Silver carp is a popular freshwater fish with a mild flavor. It was highly sought after in the 1990s due to limited supply and few edible fish species. However, modern farming practices involve excessive use of chemical fertilizers in ponds to boost the growth of plankton, which serves as food for the carp. Therefore, it is best to avoid consuming this type of fish.
4. Tilapia

Tilapia is a fast-growing, omnivorous fish with high reproductive rates and disease resistance. It feeds on decaying plants, animal waste, and carcasses.
One of the biggest advantages of tilapia is the absence of small bones in its meat, making it a favorite choice for grilling, suitable for both children and the elderly.
The cleanliness of tilapia depends largely on its living environment. It is advisable to avoid wild-caught tilapia and opt for farmed fish obtained through proper channels and subjected to quality checks.
5. Aquarium Cleaner Fish
Although aquarium cleaner fish are not inherently poisonous, they are not recommended for consumption. These fish feed on a variety of substances, including waste and the eggs of other fish, resulting in the accumulation of toxins and high levels of heavy metals like lead and mercury in their flesh. Regular consumption of this fish can lead to headaches and liver and kidney problems.
Why the Elderly Advise Against Buying Pork Neck and Catfish
“Ancient wisdom offers a plethora of insights into dietary habits and preferences. One such intriguing adage advises against purchasing pork from the neck region or choosing carp when buying fish. This advice stems from the belief that these specific parts or species may not offer the desired taste or quality.”
The Ancient Wisdom: “Don’t Buy Catfish” – But Today, a Delicacy?
The mudfish was once considered a cheap and undesirable fish, fit only for the poor. However, today it is a sought-after delicacy, prized for its unique flavor and texture. This humble fish has undergone a remarkable transformation, from a lowly and overlooked catch to a culinary favorite, gracing the tables of discerning food lovers across the land.