Goldfish Make Themselves Drunk to Survive Harsh Winters

Goldfish Make Themselves Drunk to Survive Harsh Winters

"This research emphasizes the role of whole genome duplications in the evolution of biological novelty and the adaptation of species to previously inhospitable environments", said lead author Cathrine Elisabeth Fagernes, an administrative manager at the University of Oslo.

Scientists have figured out how goldfish produce alcohol to survive when trapped beneath the icy surfaces of frozen lakes and ponds. This is an issue that many fish must deal with, typically by slowing down their movement dramatically and continuing to pull oxygen out of the water by passing it over their gills, but carp have developed a particularly robust backup system for dealing with oxygen depletion.

This diffuses across their gills into the surrounding water, helping to prevent a unsafe build-up of lactic acid in the body, making it unique among vertebrates.

Unlike most vertebrates which die within a few minutes without oxygen, goldfish and their wild relatives crucian carp are able to survive for months in oxygen-free water.

"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 study co-author Michael Berenbrink, an evolutionary biologist at the University of Liverpool. "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".

This insanely useful skill comes down to the fish having two different sets of proteins in their muscles for breaking down carbohydrates - one similar to our own and a second, unique protein that allows them to produce ethanol.

'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".