/ 24 March 2022

In the age of extinction, 212 new fish species found last year

Colourful: The Lentipes kijimuna gobi is one of two freshwater fish found on the Japanese island of Okinawa. The other gobi is Lentipes bunagaya. Both are named after woodland spirits. (Ralf Britz)

A fish named Wolverine, a blind eel discovered in the well of a school for the blind in Mumbai, and a tiny species slightly longer than a thumbnail that helps research into neurophysiology.

These are among the 212 species of freshwater fish that were formally recorded as new species in 2021 and are featured in a new report by Shoal, a freshwater species conservation initiative. 

Among them are 29 newly-described species from Africa, including three from South Africa — Amphilius engelbrechti, Amphilius zuluorum and Enteromius mandelai. A further seven new species were newly-described in Angola, while four each were formally recorded in Malawi and the Democratic Republic of the Congo. 

In Malawi, a newly-described species is Metriaclima Gallireya, rare cichlids that live in gastropod shells on the bed of Lake Malawi

Every year hundreds of freshwater fish species are discovered and described by scientists for the first time, according to the report. “Each new discovery proves there is still much about the world of wonder underneath the surface of the planet’s rivers, lakes and wetlands that remains unknown.”

On average, four freshwater fish species were described each week last year and, with about one third of freshwater fish threatened with extinction, “it is a race to discover and describe species to give them the best possible chance of survival”.

Each new species “deepens our understanding of evolution, informs knowledge of the relations between species, other organisms and their environment, and helps define conservation priorities”, Shoal says.

The discoveries can lead to research that deepens knowledge of human life. For example, the Danionella cerebrum, found in turbid streams in southern Myanmar, is used in neurophysiological research, with ramifications for understanding brain function in humans.

“This tiny critter has been sitting under the noses of neuroscientists for at least five years before it was discovered as a new species,” the report states. “Displays of complex behaviour, coupled with a remarkable anatomy where the skull roof is missing and the brain is covered by a thin layer of skin, has made Danionella cerebrum a model organism in neurophysiological research.”

Fortuitously, the bright-red Mumbai blind eel, Rakthamichthys mumba, was discovered at the bottom of a 12m well shaft in the grounds of a school for the blind. It has no eyes, fins or scales and is the first completely blind subterranean freshwater fish species to be described from the Northern Western Ghats in India.

The aptly-named Wolverine pleco, Hopliancistrus wolverine, found in the Rio Xingu basin in Brazil, possesses three stout odontodes that are concealed beneath its gill covers, which it uses defensively to stab anything threatening. “Researchers report repeatedly bloodied fingers when handling them,” according to the report.

The “fantastically colourful” Kijimuna and Bunagaya gobies, Lentipes kijimuna and Lentipes bunagaya, from Okinawa, Japan, have been named after woodland spirits of the island’s folklore.

Scientists, the report says, go to great lengths to discover and describe the planet’s amazing fish diversity, facing huge problems along the way, including lack of resources and lack of government interest, “not to mention the difficulties and risks associated with field work in regions such as the Amazon and the jungles of Southeast Asia”. 

“They face an uphill battle to describe this incredible biodiversity before it is lost forever. In this age of extinction, it is freshwater ecosystems that are the sharp end of the wedge. With myriad threats including dams, pollution, unsustainable fishing, and invasive species, around one in three freshwater fish species are threatened with extinction.”

Shoal says the 2021 edition of its report will be the first of an annual release of new species reports, to help raise awareness and increase the chances of freshwater biodiversity conservation receiving much-needed funding.

“We are excited by the opportunity to help tell the species’ stories, and hope we can draw attention to them, and encourage people to act to help save them before it’s too late,” said Mike Baltzer, its executive director.