Fish with gonads located above the head in Vietnam

In the group of plants below the slow flow of water, a 2cm male Phallostethus cuulong is approaching the female, swimming in parallel and trying to mate with it. At this time, their head is placed close together, forming a 45 degree angle.

It may sound counter-scientific, but in reality, this is the way to help males approach 'partners' , simply because their gonads are located above their heads.

P. cuulong belongs to the Priapiumfish group - a little-known fish that lives in Asia (especially Southeast Asia), whose genitalia is located under the chin, just behind the mouth, named after the fertility god. of ancient Greece, Priapus.

P. cuulong with genitalia is located just below the chin.

In July 2009, Koichi Shibukawa - an expert working at the Nagao Nature Environment Fund in Tokyo, Japan, discovered a strange fish swimming alone in a canal near the Mekong (Vietnam) area. Working with colleagues at Can Tho University, he realized it was a completely new species.

Priapiumfish male has no penis like humans and many other mammals. Instead, they have a single reproductive organ called a priapium , which lies backwards. It looks like another type of pectoral fins. In addition, the oviduct of the female Priapiumfish tends to be filled with sperm in the body and therefore, the percentage of fertilized eggs is quite high.

Although no one has witnessed the process of mating of P. cuulong so far, the conclusions are still based on observations from many other similar species. Scientists are still unable to find out why Priapiumfish has developed this extremely special gonad, said Lynne Parenti, a researcher from the Smithsonian Institution in Washington, DC.