Goldfish use alcohol to survive in icy waters, scientists find

The goldfish keeps itself warm in icy water with alcohol. Picture: SWNS
The goldfish keeps itself warm in icy water with alcohol. Picture: SWNS
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Goldfish create alcohol to survive below icy surfaces, scientists have discovered, enough to exceed the drink-driVe limit.

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Researchers from the Universities of Oslo and Liverpool have unearthed the unique solution to surviving for long periods in oxygen free water, namely frozen lakes and ponds.

Most vertebrates die quickly in such conditions but goldfish and crucian carp are able to survive for months.

Their molecular make-up sees the fish convert their anaerobically produced lactic acid into ethanol spreads across their gills and into the water.

They possess specific sets of proteins which usually generate energy through carbohydrates towards their breakdown within a cell’s mitochondria.

One of the proteins is identical to what others species have. However, the second is different, allowing them to survive despite the lack of oxygen.

Dr Michael Berenbrink, an evolutionary physiologist at the University of Liverpool, said: “During their time in oxygen-free water in ice-covered ponds, which can last for several months in their northern European habitat, blood alcohol concentrations in crucian carp can reach more than 50mg per 100 millilitres.

“However, this is still a much better situation than filling up with lactic acid, which is the metabolic end product for other vertebrates, including humans, when devoid of oxygen.”

Meanwhile, Lead author Dr Cathrine Elisabeth Fagernes, from the University of Oslo, said: “The ethanol production allows the crucian carp to be the only fish species surviving and exploiting these harsh environments.

“Thereby avoiding competition and escaping predation by other fish species with which they normally interact in better oxygenated waters.

“It’s no wonder then that the crucian carp’s cousin the goldfish is arguably one of the most resilient pets under human care.”