How a goldfish manages to tolerate the extreme, oxygen-depleted environments of frozen lakes for up to months at a time has often puzzled biologists, but new research has found that it's down to some locally brewed alcohol.
This diffuses across their gills into the surrounding water, helping to prevent a risky build-up of lactic acid in the body, making it unique among vertebrates.
The process, which is unique among vertebrates, is more commonly associated with brewer's yeast.
"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 milliliters, which is above the drink drive limit in these countries", said Dr Michael Berenbrink, an evolutionary physiologist at the University of Liverpool in the United Kingdom, on Friday.
Dr Michael Berenbrink, an evolutionary physiologist at the University of Liverpool, said that the blood alcohol concentration in these fish can exceed the drink-drive limit during the winter.
Crucian carp are also capable of creating ethanol as a survival tool for harsh winters
The researchers from the Universities of Oslo and Liverpool have discovered the unusual molecular mechanism behind this unique ability. "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".
They possess specific sets of proteins which usually generate energy through carbohydrates towards their breakdown within a cell's mitochondria.
In trying to explain the possibly evolutionary goal of the unique trait, lead author of the paper Dr Cathrine Elisabeth Fagernes 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".
For those of you reading this after a boozy night on the town be warned - putting your goldfish in the freezer and then sucking it isn't going to get you more drunk, so don't try it. ®.