Formalin In Fish: How To Detect The Cancer-Causing Chemical Contamination in Your Seafood
Formalin in fish (Photo Credits: Pixabay)

Fish lovers all over the country have become wary of feasting on their favourite food as news of fish contamination first broke out in June. The Kerala Food Safety and Fisheries Department seized close to 12,000 kg of fish from two districts that were laced with formalin as part of Operation Sagar Rani. Following the discovery, nine states – Goa, Assam, Nagaland, Manipur, Tamil Nadu, Kerala, Meghalaya, Odisha, Andhra Pradesh and Mizoram -- In the light of the discovery, many fish eaters are led to contemplate whether it is safe to eat fish anymore.

What is Formalin?

Formalin is a known carcinogen, which can cause cancer if taken for a long time. The chemical is a colourless solution of 37 percent formaldehyde and water, used mainly to preserve organic specimen such as dead bodies. When used in food, it can help in increasing its shelf life, which explains why formalin was found in the fish consignment in the first place.

How To Test Whether The Fish is Safe

If you are a fish eater, it’s natural to be concerned about your and your family’s health. But instead of shunning fish completely, there are certain tests you can personally perform to find out whether the fish is worth consuming.

Stiff Scales:

Fish treated with formalin don’t look fresh. The scales may be stiff and hard. Running your fingers along the scales will give you an idea whether the fish is fresh or not.


If there is formalin contamination, the fish may have an uncharacteristic odour, not common to seafood. It may give out a strong, pungent smell.


Normally, flies are a common sight at the fishmonger's. But flies don’t swarm around fish treated with formalin.

Chemical Kits

Those who want to be extra careful, about the formalin content can always buy a chemical testing kit with 25 strips, each priced at Rs 3. To check the fish, keep a strip on the surface of the meat and watch for any colour change. If the colour of the strip changes into dark green to blue colour, it contains formalin.

As of now, we cannot gauge how prolific the contamination is. But it’s best to be careful. Ingesting formalin can cause a lot of gastrointestinal concerns like vomiting, diarrhoea, upset stomach, liver problems, skin diseases, etc. apart from cancer. Ideally, it’s best to wash out the fish thoroughly before cooking it by leaving it under running water for a while.