Scientists have discovered how goldfish and their wild ilk survive months of winter in frozen-over lakes of oxygen-free water.
The answer is alcohol – the cause of, and solution to, all of life's problems.
There aren't many vertebrates that can survive without oxygen.
However, goldfish, and their wild relatives, the crucian carp, share a genetic mutation that allows them to anaerobically convert excess lactic acid into ethanol and flush it out of their gills.
The fish are thought to be the only known vertebrates with this talent – the more's the pity.
"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 UK, on Friday.