Despite everything we as humans may be doing to catapult the ecosystems of the world toward extinction, a new report on an amazing array of fish species first classified in 2022 shows precisely how fiercely the will to survive and evolve still lives on.
Thanks to the impacts of air pollution which settles in lakes, streams, and waterway; industrial waste, sewage, and agricultural runoff; and heating of the planet due to the climate crisis; the habitats where freshwater fish live have been badly damaged over the last five decades. It is why nearly 75% of all freshwater populations have died off in that time.
This death cycle is important to us not just as a measure of our collective abuse of nature. We must also take note of it because 70% of the food chains on the planet link back in one way or another to the species who live, give birth, die, and attempt to evolve in their homes in the world’s freshwater wetlands, lakes, ponds, rivers, streams, and tributaries. What we do to these species we ultimately do to ourselves.
This all is in part why the New Species 2022 report, published by SHOAL in partnership with the International Union for Conservation of Nature (IUCN) Species Survival Commission (SSC) Freshwater Fish Specialist Group (FFSG) and the California Academy of Sciences, is both so important and surprising to read.
SHOAL, which headed up this study, produced the latest report as part of its global initiative to halt extinctions and recover populations of the most threatened freshwater species around the world. It is based in the United Kingdom and is a program of Synchronicity Earth and Re:wild.
This year’s study revealed 201 new freshwater species. 43.8% of those catalogued as new this year came from South America and 33.8% from Asia. Simply because of the challenges involved in finding and analyzing them, it is safe to say these are just a sample of what nature has surprised us with over the last year. But what they have discovered is amazing, ranging from simply beautiful to spectacular in showing off the magic of evolution.
The Black Tiger Dario fish. Photo: SHOAL
As an example, consider the Black Tiger Dario, also known as the Juan Deriba killifish. This species, which was discovered in the Bolivian rainforest located north of Santa Cruz, has adapted to its environment by jumping out of the streams it lives within when a perceived predator is present. It can jump as far as 30 to 50 centimeters (roughly 12 to 20 inches) at a time. Not only can they do this, they also have the ability to survive out of any water for as long as three weeks, as long as the air around them is sufficiently humid.
The family of killifish the black tiger dario evolved from are also already noted for their ability to survive in drought for relatively longer periods of time. That is an especially important characteristic in a world already growing hotter and drier every year.
Also, even though this is a newly documented species which other evidence suggests does not exist in large numbers and is already highly threatened by agricultural runoff which has harmed its local habitats, it appears its unique characteristics could help it thrive even while other species might not.
That is the conclusion of Heinz Arno Drawert, Associate Researcher at the Museum of Natural History Noel Kempff Mercado, and representative for the Bolivia of the Killifish Foundation, who discovered the black tiger dario and secured the first samples of the new variant. He believes that if the species can be allowed to propagate within the forests themselves, especially where small puddles of water may assist this jumping fish in surviving when they land, the species has a good chance of continuing to reproduce and thriving for awhile longer.
Drawert himself is typical of the many researchers who helped discover and document the many new fish revealed for the first time in this latest report from Shoal. He is a native of the region, having come here with his parents in the early 1990s. They moved here when they purchased the Juan Deriba ranch, a 700-hectare ranch. As a child, Drawert spent much time exploring his surroundings, and on one of his early outings there – in 1996 – he found what he believes was the earliest identified example of the black tiger dario. Despite that early find, it was not until 2022 that Drawert was able to secure samples of the fish for scientific evaluation to confirm that it was a genuinely new species.
The Kalimpa'a ricefish. Photo: SHOAL, ©Zulfadli
The Kalimpa’a Ricefish, also known by its Latin species name of Oryzias kalimpaaensis, represents another intriguing adaptation to its habitat.
This species, located in Indonesia at Sulawesi’s Lake Kalimpa’a in Lore Lindu National Park, is what is known as a pelvic-brooding fish. Unlike most freshwater fish which deposit their eggs on a substrate after being fertilized, pelvic-brooding fish carry their fertilized eggs on their underbellies to shield them from predators. This particular variant of pelvic brooders incorporates extended pelvic fins as an additional evolutionary benefit to protect the eggs from potential harm. These fish never release their eggs until the larvae begin to hatch.
The Kalimpa’a Ricefish is unique in two other ways. It is one of only five known pelvic-brooding ricefish. Its primary habitat at the lake, located 1,66 meters (5,446 feet above sea level), also represents the highest altitude where any ricefishes have been found.
This species was discovered and identified by Abdul Gani, a Lecturer at the Faculty of Fisheries, University of Muhammadiyah Luwuk, in Sulawesi, Indonesia. His team regularly seeks out new species at Lake Kalimpa'a, one of the world's most active "biodiversity hotspots", especially with regards to freshwater fish. He is currently working on a doctoral thesis based on this new species and its "sister" fish Oryzias bonneorum.
As a final example from the report, the Paracanthopoma vampyra and eight other members of this fish family is one of the most bizarre.
Paracanthropoma vampyra, a fish which lives solely on a blood diet. Photo: SHOAL
Found in rivers in Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru and Venezuela, these creatures are the only jawed invertebrates on the planet — other than vampire bats — that feed on blood as their only source of food. They are part of the vandelliine genus of fish, a group which includes often extremely small blood-eating fish which have the ability to swim up the urethra of other creatures and then rip internal organs to get their food. And yes this does include human urethras for those who find themselves swimming at the wrong time in the waters of the Amazon and others, though those cases are extremely rare.
The newly discovered variants are all part of the Paracanthopoma genus, which include versions which attach themselves for long periods of time — semi-permanently, in fact — to the bodies of their hosts from the outside.
Besides the 201 new fish species discovered in 2022, the report also takes time to highlight those whose brilliant and tireless contributions made those identifications possible.
One of the most prolific of those scientists last year was Dr. Roberto Esser dos Reis, a Brazilian ichthyologist, professor and Curator of Fishes at the Pontifical Catholic University of Rio Grande do Sul. In a career lasting multiple decades, his team of students and others has been responsible for the discovery of 139 new species, 151 new taxa, and 17 new genera of fish. In 2022 alone, his group identified eight new species and one new genus of freshwater fish. In 2023 they have already added another to that number; it will become part of the 2023 edition of the annual SHOAL report.
The new report was released on March 3 in honor of World Wildlife Day, an annual celebration of the glorious biodiversity of the planet and reminder of the necessity of preserving it.