Fisheries Food Science

Fishy Business – The issue of Formalin

The consumption of fish has lately seen an upward trend and with it, the issue of adulteration of fish with unapproved chemicals and additives has also come into the light. Formalin which is formaldehyde in water is a common adulterant in fish. Traders and suppliers use it to extend the storage life of fresh or chilled fish and artificially improve the sensory attributes.


The recent issue in Chennai gives strong support to the above statement.  As many as 11 out of 30 samples of fish purchased from Chintadripet and Kasimedu, the two major fish markets in Chennai, on two different days have tested positive for formalin. This was the first time samples of fish in Tamil Nadu have tested positive for formalin.


Food Safety and Standards Authority of India (FSSAI) officials have been undertaking tests at the fish markets and harbours across the State to test for formalin following a scare in neighbouring Kerala that fish sourced from here were chemically contaminated.


Compelling reasons for Formalin usage

The underlying motive of using formalin on fish is to extend the storage life of fresh or chilled fish and to artificially improve the sensory attributes i.e. appearance, so as to give a facade of fresh fish. In most cases, the traders use formaldehyde to prevent the spoilage and keep fish in marketable conditions. Unavailability of good quality ice at harvest centres, inadequate insulation during domestic transport and lack of warehousing facility for bulk storage of fish are some of the compelling reasons for rampant use of formaldehyde in domestic fish marketing. The added formaldehyde content in fish will decrease during storage due to loss along with the ice-melt water, but cannot be fully removed. As this solution is widely available in market, fish traders and suppliers have easy access to it for adulteration.

Formalin – a carcinogenic

The International Agency for Research on Cancer (IARC) of WHO classifies formaldehyde as carcinogenic to humans, with sufficient evidence for causing nasopharyngeal cancer in humans with occupational exposure, although no carcinogenicity is so far established ingestion route. Presence of formaldehyde in food at higher levels can lead to severe abdominal pain, vomiting, coma, renal injury and possible death. For food handlers, it can lead to sensory irritation of eyes and lungs, dermatitis and asthma. As per the United States Environmental Protection Agency (USEPA) the maximum daily dose reference is 0.2 mg per Kg body weight.


Rapid kit helps it’s detection

The Central Institute of Fisheries Technology (CIFT) has developed a kit for easy and quick detection of adulterants in domestically marketed fish. The two kits, one for ammonia and other for formaldehyde include thin strips and a small solution. A person wanting to test the fish will just have to remove the strip and scrape it on the fish. Then put one drop of test solution on the paper strip and watch the colour change.

Fishy Business - The issue of Formalin
Source: The Hindu

In case of formalin, if the colour that appears on the strip is light pink, then the samples are free of formalin. If the strip turns green on adding the solution and further develops into deep blue, then in that case the level of formalin will be 20 to 100 mg per kg, which indicates the fish is not safe for consumption.  The colours are indicated on the standard charts so that a consumer can get the result on the spot. The result is obtained within a short span of 2 to 3 minutes. CIFT has called for the Expression of Interest for the transfer of technology to the industry. The kit is ideal for fresh fish. In stored fishes, ammonia cannot be detected but formaldehyde presence can be known. As of now, the detection kit includes 25 nos. Of testing strips, reagent solution and standard chart for colour comparison. Currently, the solution validity is for a month but the institute is working to improve it. The strip has an expected cost about Rs 1 per strip in commercial production.

Being a non- destructive, simple, consumer friendly and cost effective detection method, this technology will awaken the fish consumers regarding safety and quality aspects of fishes available in the market, which will indirectly discourage the malicious adulteration by the traders in the sector.



Srilavanyaa. K is a graduate of Food Process Engineering from Tamil Nadu Agricultural University. Her passion for the food sector and writing has brought her to the Agraria magazine. Being a part of food industry, food safety is her prime concern. She finds at most satisfaction in penning down articles about it and considers a step forward in her career.