After the Nepal flash floods, Bihar’s Animal and Fisheries Resources Department has advised people not to buy, sell, or consume fish caught in floodwaters. “Fish contaminated, advised to avoid eating,” a post on its X handle read.

What happens when you consume such fish? Experts elucidate.

During a flood, the usual boundaries between rivers, ponds, drains and sewage channels disappear. “Fish can get swept into water contaminated with sewage, animal waste, dead animals and other pollutants. This means the fish may carry microorganisms not normally present in their usual habitat. The concern is not about fish as a food itself, but about the environment they have been exposed to. Until the water bodies return to normal and the fish are considered safe by the concerned authorities, it is better to avoid them,” cautioned Dr Saiprasad Girish Lad, consultant gastroenterologist, Wockhardt Hospitals Mumbai Central.

Thousands of corpse-eating fish of the Trishuli River, known there by the name Goonch Catfish have reached Bihar with the flood waters . These are large, lazy fish that resides in the river near the cremation ghats built along the riverbank and feeds on half-burnt corpses, which… pic.twitter.com/AQGne4dxuo

— Amitabh Chaudhary (@MithilaWaaala) August 31, 2026

Dr Shankar Zanwar, senior consultant gastroenterologist at Gleneagles Hospital, Mumbai, concurred and said that fish caught from contaminated water may not always look, smell, or taste different, making it difficult for consumers to tell whether they are safe.

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What can happen if someone eats such fish?

The immediate concern is food-borne illness. “Depending on what the fish has been exposed to, a person could develop vomiting, loose motions, abdominal cramps, nausea or fever. In some cases, contaminated food can cause significant dehydration, particularly in children, older adults and people with other health problems. Certain bacterial and viral infections can also become more serious if treatment is delayed,” said Dr Lad.

The Dairy, Fisheries and Animal Resources Department has issued an advisory regarding fish arriving in Bihar from Nepal.

It has been warned that consuming fish that appear strange or unusual could lead to illness pic.twitter.com/SY0Ohzw2kC

— Bihar_se_hai (@Bihar_se_hai) September 1, 2026

In some cases, contaminated food can lead to serious food-borne infections, particularly in young children, older adults and people with weakened immunity. “Floodwater can also contain chemical pollutants, which may accumulate in fish,” said Dr Zanwar.

Does thorough cooking make floodwater fish safe?

According to Dr Lad, cooking reduces the risk of many bacteria and parasites, but it should not be considered a guarantee of safety when the fish’s source is uncertain. “There can also be contamination during handling, cleaning and preparation. So, if the fish has been caught directly from floodwaters or is unfamiliar in appearance, the safest approach is simply not to consume it,” said Dr Lad.

Cooking can kill many germs, but it does not necessarily remove all chemical contaminants or toxins, affirmed Dr Zanwar. “Therefore, washing or thoroughly cooking a fish caught from contaminated floodwater does not guarantee that it is safe to eat,” added Dr Zanwar.

मछलियां हुईं दूषित, खाने से बचने की दी गई सलाह#जनहित_में_आवश्यक_सूचना #सावधान_रहें #नेपाल_बाढ़ #बाढ़_से_आई_मछलियां #अज्ञात_मछली #मत्स्य_पालक #बिहार_सरकार#PublicAdvisory #NepalFlood #FloodAlert #FishSafety #DoNotEat #DoNotSell #BiharGovernment pic.twitter.com/DP7lqNVAnD

— Dairy, Fisheries and Animal Resources Dept., Bihar (@BiharAFRD) September 1, 2026

What should someone do if they have already eaten such fish?

There is no need to panic if the person feels completely well, but they should monitor themselves for symptoms such as repeated vomiting, diarrhoea, abdominal pain, fever, dizziness or breathing difficulty. “Persistent vomiting or diarrhoea can lead to dehydration and requires medical attention. Anyone developing significant or unusual symptoms after eating such fish should consult a doctor promptly rather than self-medicating,” said Dr Lad.