The male molly fish, found in Mexico, sports a “sexy” moustache, so that it might appear more attractive to females of the species.

Scientists were completely baffled as to why this strange Mexican fish would have a rather elaborate moustache-like structure on their top lip.

Some light has now been shed on the subject, it has been found that this “moustache” is actually sexually attractive to potential mates, and it is likely a key factor in the mating process.

Not only does this frisky molly fish use its moustache for show, but it may also be used in a kind of fish foreplay, exciting females by rubbing their genitals.

The details of this are published in the journal Behavioral Ecology and Sociobiology.

As the name suggests, Mexican mollies make their home in Mexico, living in a range of locations from creeks, to lakes, and even small rivers.

Mexican mollies have a rather complex mating behavior, with the males fertilizing the females internally, rather than just spraying their sperm over externally laid eggs, like so many other fish species.

Mine is Bigger Than Yours!

Not all male Mexican mollies are created equal however. Some of them have a moustache-looking structure jetting up from the scales on their top lip.

Until quite recently, the function of this moustache has not been known, and no one has bothered to look deeper into the matter.

So a crack team of scientists, which include Professor Ingo Schlupp of the university of Oklahoma, collegues in the US and Germany have decided to delve into it for the first time.

They trapped a wide selection of both male and female Mexican mollies, to measure the length of the moustache on those that had one.

They then proceeded to run a myriad of tests, and females consistently preferred males with moustaches over ones without. Of course, the bigger the moustache the more attention the males received.  This shows once and for all, that the barrier between fish and man.. Is not so great after all.

Hanky Panky in the Tank:

Even though the group has only tested the visual attractiveness of the moustache, there is evidence to suggest that it also plays a more tactile role. Professor Schlupp has told the BBC “This is based on the general observation that males will touch the female’s genital region with their mouth prior to mating,”

This unusual behavior has become known as “nipping” and is being pursued diligently by the group of scientists.

The common consensus is that by rubbing their moustache on the genitalia of the females, they are simply advertising their attractiveness. Some other species of catfish have comparable features, and have unknown functions.

Some scientists have also speculated that this moustache may act to attract more food as well, which is a desirable trait in the fish kingdom.

The group will continue to study the Mexican Molly’s moustache, until then, it will have to be boiled down to sex appeal.