As a way to survive harsh winters under frozen lakes, this goldfish has been discovered to produce alcohol. In this way, they can survive for days, even months, in oxygen-free water at the bottom of ice-covered ponds .
How does the process work?
What they do is convert anaerobically produced lactic acid into ethanol, which then diffuses through their gills into the surrounding water and prevents a dangerous build-up of lactic acid in the body. The process has recently been discovered by a team from the Universities of Oslo and Liverpool. As explained by Michael Berenbrink , an evolutionary physiologist at the University of Liverpool:
During their time in oxygen-depleted water in ice-covered ponds, which can last for several months in their northern European habitat, alcohol concentrations in crucian carp can reach more than 50 mg per 100 milliliters, which is above the limit. of the drinking capacity in these countries. However, this is still a much better situation than filling with lactic acid, which is the end metabolic product for other vertebrates, including humans, when they lack oxygen.
Ethanol production allows crucian carp to be the only fish species to survive and exploit these harsh environments, thus avoiding competition and escaping predation by other fish species.