Tiny Fish With Superhero Name Rediscovered After Nearly 50 Years

A small, critically endangered fish was recently found by Turkish ichthyologists in two streams in southeast Turkey. It’s the first time the Batman River loach has been spotted since 1974.

The loach was part of the Search for Lost Fishes project from Re:wild and Shoal. Re:wild is an organization launched in early 2021 by a group of conservation scientists and Leonardo DiCaprio, a longtime supporter of environmental and conservation issues. Re:wild’s mission is to protect and restore the biodiversity of life on Earth. Shoal is a global initiative for freshwater species conservation.

The Batman River loach was on the group’s 10 most wanted list of freshwater fish that haven’t been seen in at least a decade.

When she heard about the search, Cüynet Kaya, associate professor with Recep Tayyip Erdogan University in Rize, Turkey, set out with research fellow Münevver Oral to look for the fish.

“Two of the 10 most wanted fish species were distributed in my country. It is a very different feeling when you see naturalists from foreign countries caring about an endemic species in your country and making efforts to save it,” Kaya says. “As a freshwater fish taxonomist, I thought that I should do my best for this project, and fortunately our efforts resulted in finding the first lost endemic and critically endangered Batman River loach.”

The Batman River loach is a small yellow and brown striped fish that grows up to 1.4 inches (36 millimeters) long. It was once commonly found in the streams and tributaries of the Batman River. The river is not thought to have taken its name from the superhero, but instead from the neighboring Bati Raman mountain.

Batman River Loach (Paraschistura chrysicristinae) was first described and named in 1998 based on four fish collected in 1974, Kaya tells Treehugger. Since then, the species has never been found despite many attempts by international teams of researchers over the past several decades.

Kaya and Oral searched the streams using tight-weave nets that prevented the small fish from slipping through and evading capture. They found 14 fish in the Sarim Stream and nine in the Han Stream.

“Morphologically speaking, Batman River loach has characteristic vertical banding on dorsal which is lost under stressful conditions. Therefore, I did not immediately recognise the species as they were losing abovementioned characteristic bands,” Kaya says. “As I spent more time in the creek I saw an individual with this banding as soon as I removed the fish out of water from its natural habitat and I got excited.”

Conservation and Preservation

Kaya and Oral said the river loach population appears steady, but they are worried about threats from pollution, drought, and invasive species on the fish’s population.

“Based on our experience, the most significant threat is the construction of dams in years between 1986 and 1999. Therefore, we focused our search on upper parts of Batman dam and their drainages thinking that lower parts of the river has been through habitat degradation thus the drop of population,” Kaya explains.

“Pollution is another threat in the river as is common in many parts of the globe. There are several villages alongside the Batman River. We have only observed a few individuals of Carassius gibelio (Prussian carp or Gibel carp) during our expedition which is known as an invasive species that might be another potential threat.”

A field study is the next step in order to determine the loach’s conservation status. Researchers will investigate nearby streams with similar characteristics to see if the Batman River loach exists there too.

“Our first goal for the protection action plan of the Batman River Loach is to determine the exact distribution area and population density of the species,” Kaya says.

“Unlike many of its congeners, it prefers to live in the fastest flowing sections of shallow streams. This shows that it can withstand fast flowing water and is a relatively vigorous species. Once the exact distribution area and population density have been determined, we will be able to re-assess the conservation status of the species.”

Importance of the Discovery

Scientists are celebrating that the loach has been rediscovered as some had feared that it had become extinct.

“When we launched the Search for the Lost Fishes, we hoped that we would have the opportunity to celebrate days like this,” said Mike Baltzer, Shoal’s executive director, in a statement. “There are so many lost and threatened fish and we are so happy that this little loach has been found, and hopefully we can now secure its future. This is the first species of Lost Fishes that has been rediscovered – hopefully the first of many.”

Kaya says the discovery is not only important for the species, but also a key source of motivation for researchers.

“There is no such a thing as un-important species in ecology. Ecosystems are organised in a state of balance where all species coexist with other species. Any change that happens can shift from a state of balance to a state of imbalance, which we face almost daily due to global warming,” she says.

“Additionally, natural and/or man-made disturbance disturb the natural balance of the ecosystem. We must not forget that all is connected in an ecosystem. When you remove a species from the natural ecosystem it collectively reflects on the ecological balance.”