Goldfish produce alcohol to survive without oxygen, discover scientists

Scientists at the University of Oslo in Norway and University of Liverpool in UK have discovered a noteworthy ability of goldfish to produce alcohol in order to sustain its survival during rough winters beneath frozen lakes.

If humans and other vertebrate animals are taken into consideration, a lack of oxygen could kill them wihtin a few minutes. Yet goldfish as well as their wild relatives, crucian carp, can survive for days, even months, in ice-covered ponds where there is no supply of oxygen.

At this point of time, the fish are able to convert anaerobically produced lactic acid into ethanol, which then diffuses across their gills into the surrounding water and avoids a dangerous build-up of lactic acid in the body.

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The study that is published in  journal Scientific Reports, shows that muscles of goldfish and crucian carp contain two sets of the proteins normally used to channel carbohydrates towards their breakdown within a cell’s mitochondria- a key step for energy production.

Dr Michael Berenbrink from 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.", he further added.

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"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.", Dr Cathrine Elisabeth Fagernes, lead author of the study said.