Scientists reveal how goldfish make alcohol to survive without oxygen

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Scientists at the Universities of Oslo and Liverpool have uncovered the secret behind a goldfish's remarkable ability to produce alcohol as a way of surviving harsh winters beneath frozen lakes.

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 50 mg per 100 millilitres, which is above the drink drive limit in these countries.

"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."

Lead author Dr Cathrine Elisabeth Fagernes, from the University of Oslo, said: "This research emphasises the role of whole genome duplications in the evolution of biological novelty and the adaptation of species to previously inhospitable environments.

"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."