Survival of the fittest means getting drunk in frozen waters for goldfish.
Goldfish create alcohol to survive below icy surfaces, scientists have discovered, enough to exceed the drink-driVe limit.
We all know that breathing oxygen in frozen waters is almost improbable but goldfish seem to just slow down a bit and are not too bothered by a low-oxygen environment even in long periods. Their bodies have a remarkable ability for producing alcohol. 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.
In order to determine just how the Carassius fish does this, the researchers grouped crucian carps and placed them in airless tanks for about a week.
It may not keep them from going belly-up if you take a vacation and forget to have a friend feed them, but that lowly little goldfish on your countertop is one heck of a survival specialist.
They have pinpointed sets of proteins which are normally used to produce energy by channelling carbohydrates towards their breakdown within a cell's mitochondria.
While one set of the proteins appears in other species, the existence of second set in goldfish is unusual. This enzyme basically ensures that goldfish will only release ethanol through the process of fermentation instead of the more risky lactic acid.
Goldfish can not survive without oxygen due to the alcohol.
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.
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The fish produced two types of similar enzymes necessary in the processing of glucose.
The research team hopes that other researchers would study and compare other species to determine whether there are differences in the process of alcohol production.
"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", said lead author Dr Cathrine Elisabeth Fagernes, from the University of Oslo.