“Many areas that could only be reached after days in a boat or in a helicopter 20 years ago and now crossed by highways.”

Maurice Kottelat has discovered and described hundreds of freshwater species: 471 species descriptions, to be precise, and an unknown number of discoveries, and has published exactly 400 papers and books in a remarkable career that spans five decades.

Although he has spent the majority of his career focusing on species in Southeast Asia, he literally wrote the handbook, alongside Dr. Jörg Freyhof, on European freshwater fishes and, with Dr. Tan Heok Hui, discovered the world’s smallest fish, Paedocypris progenetica.

What is it about discovering and describing species that particularly appeals to you?

MAURICE: In most cases the discovery is a by-product of surveys or other work for clients; but in these cases, I usually accept the job only if it allows travel to interesting places (i.e. where I have not been before, preferably where no other ichthyologist has been, and where I am allowed to take samples to examine and study). When it comes to non-commercial activities, I am interested in places I have not been and where I expect there will be novelties.

Discovering new species is not my primary aim; it is a nice by-product demonstrating that the selection of the area was correct, or that the money was well spent. My primary interest is faunistic and inventories, landscapes. But it is fair to say that the output is often calculated as a number of species, especially new species.

To be frank, describing is boring and repetitive. It was interesting at the beginning, to show what was being discovered. But now it is linked with administrative burden (submissions, reviews, revisions, etc. Now I prefer writing books or large papers or describing species in bulk). Obviously, there is a fair amount of ego!

Also, I write because I sort of feel an obligation to make information public, for others to use for conservation, to leave a record of what existed before the construction of dams and highways, before an influx of tourists etc. I think this is a kind of moral duty. It makes me angry to read colleagues writing about a pristine lake when their pictures show something totally different from what I saw when I visited the same lake years ago.

Can you talk through the process of going out into the field to search for fish?

MAURICE: If you mean how to find new species, it is all about the instinct to select places and habitats that have not been sampled before – rapids, waterfalls, deep swamps, anything weird that people would usually avoid – and look for small fish. In fact, you can look just about anywhere there is water, including puddles and saturated soils.

How many times have you been to the field recently?

MAURICE: In the past three years, thanks to COVID, not once. But I will hopefully go back to Laos in March. Before COVID it was about two to three times per year.

What was a particularly memorable species discovery?

MAURICE: A trip to Laos in 1999 yielded about two new species per day for a month and a paper describing 62 new species in one shot.

At that time, the published information on the fishes of Laos was more or less restricted to the Mekong. In 1999, an environment department at the World Bank (through Tony Whitten) had a programme to translate field guides from English, French, German etc into the local languages. I was asked if I could compile these reports into a single volume to be translated into Lao. I objected because there were too many blanks on the map (areas where I had not sampled were, at that time, areas where few or no ichthyologist had ever been). I negotiated to write the book only if there was funding to fill the main gaps.

I spent one month fishing in selected river basins and ‘creamed’ the easily accessed areas. Because of the publication deadline and the need to have valid names for the species, I had to rush a paper diagnosing as many of them as possible, which ended in a paper describing 62 new species and one new genus.

The book came out in 2001 and the Lao version was distributed for free to fisheries and conservation agencies, NGOs, high schools and other places.

Before I started work on fishes of Laos, about 210 species had been recorded in the country, all in the Mekong. The 2001 book includes 480. The next edition, to be published this or next year, includes 570 named species, with about another 50 unnamed species I’ll try to add.

What sorts of places are likely to have undiscovered species living in them?

MAURICE: Habitats: headwaters, rapids, wet soil, caves, swamp forests, deep water, in fact everywhere where there is water.

Areas: Southeast Asia, Myanmar, northeast India, central Borneo, southwest Asia. New species are still being discovered in southern Europe!

Are there any places you’d particularly like to target?

MAURICE: There are still places in Laos where I have not been. I still have an interest in Borneo but local conditions (especially red tape) make it a pain. I have been to Mongolia and, despite depauperate fauna, I would like to visit again. But with age, I prefer to focus on what I know best.

You’re potentially the only person in the world who has built a career flying round the world getting paid to discover and describe freshwater fish species. What was your route into that?

MAURICE: Not around the world, Asia and southern Europe are enough.

I worked in a research institution and became unhappy with several conditions and resigned.

I was quickly asked to do surveys, for conservation agencies and NGOs, then for EIAs of hydropower, mining, forestry projects. I was not paid to discover new fish species, but I took time to do real surveys and brought proof of what I reported, which leads to discoveries.

The scientific surveys were mostly without salary, though they did pay for field expenses.

When I was much younger, it was not my ambition to describe fish but to travel and see fish in their habitat.

What sorts of changes have you seen to freshwater habitats and species throughout your career?

MAURICE: Many areas that could only be reached after days in a boat or in a helicopter 20 years ago and now crossed by highways. Some habitats have been greatly reduced, e.g. peat swamps, or have disappeared.

Some species have become very rare and fish densities have become very low because of overfishing. Introduced species are more and more present. Even in protected areas, aquatic habitats are not given attention, and fish are seen as a resource or as food for waterbirds, not as species in themselves. A kilogram of introduced tilapia has more value than a kilogram of 20 small endemic species.

SHOAL released their annual report New Species 2022 on World Wildlife Day, Friday 3rd March 2023. The report details the 201 species of freshwater fish identified in 2022.

“We know that Sulawesi is a hotspot for freshwater biodiversity, and I think we have to explore it more.”

Abdul Gani is a Lecturer at the Faculty of Fisheries, University of Muhammadiyah Luwuk, Central Sulawesi, Indonesia, and an advocate for Sulawesi’s diverse and abundant endemic freshwater species. He discovered and described the Kalimpa’a ricefish highlighted in New Species 2022.

What do you enjoy about discovering and describing species?

ABDUL: One of my passions is exploring the world around me, especially because I know that the island of Sulawesi is included in the Wallacea designation, and is a biodiversity hotspot, especially freshwater ichthyofauna. There are many places on the island with incredible diversity of ichthyofauna, and I love to explore the island and learn about the creatures there. Describing species is a good challenge that adds to the exploration.

In 2020, my team and I discovered a new endemic species from the Adrianichthyidae family in Lake Kalimpa’a, Lore Lindu National Park, which we described in 2022 and named Oryzias kalimpaaensis1.

In my opinion, there are still many freshwater fish species that can be obtained and described as new species because Indonesia has a high level of diversity and the exploration of freshwater fish in Indonesia is still low. This can be an opportunity to find new freshwater fish species.

What has been a particularly memorable species discovery for you?

ABDUL: The most memorable species discovery for me was when I discovered the new species Oryzias kalimpaaensis in Lake Kalimpa’a, Lore Lindu National Park in 2020 and published in 2022.

Also, in 2017 my team ERA Indonesia and I found a species that had not been seen for a long time: Oryzias bonneorum in Lake Lindu. This species was described by Parenti in 2008, based on specimens preserved since 1939. But we have not published the paper about that yet.

My plan is for Oryzias bonneorum and Oryzias kalimpaaensis to become my next research project for the dissertation material in my Doctoral programme. ERA Indonesia is a community of young people who focus on preserving biodiversity, especially endemic flora and fauna.

Could you describe the process of discovering Oryzias kalimpaaensis?

ABDUL: It started through my hobby of adventuring in the wild. When I was in high school, I joined a community of nature lovers, which led me onto discovering and describing new species.

From 2020 until now, my team ERA Indonesia and I have been exploring the river and lake in the Lore Lindu National Park along with Fish Quarantine Station Quality Control and Safety of Fishery Products (SKIPM) Palu, Indonesia, with the purpose of collecting data about invasive species and finding new species.

During one of these explorations, we found this new fish from the Oryzias genus that had not been identified before. In the next exploration, we took measurements of the water quality and prepared several specimens for morphological and molecular identification. Based on the results of morphological and molecular identification, we found this was a new species from the Adrianichthyidae family and Oryzias genus. We named it Oryzias kalimpaaensis after the name of the place where the fish was found, Lake Kalimpa’a.

Why do you think Oryzias kalimpaaensis was not discovered before?

ABDUL: Freshwater fish exploration hadn’t then been carried out there, so the existence of the species wasn’t known.

What notable things can you tell us about the species?

ABDUL: The discovery of Oryzias kalimpaaensis is a remarkable achievement for me personally and also for my friends who are involved in the exploration and writing up of the publication. The discovery gives new information about the diversity of Sulawesi’s endemic species, especially in Central Sulawesi. Central Sulawesi’s freshwater endemics are now 16, whereas in 2019 it was 15.

We know that Sulawesi is a hotspot for freshwater biodiversity, and I think we have to explore it more. With that in mind, I think the discovery of Oryzias kalimpaaensis could be the start of other endemic species being discovered in the area.

I hope that the diversity and populations of freshwater endemics in Sulawesi sustains and thrives: let’s protect and preserve Sulawesi’s endemic freshwater!

1 https://www.researchgate.net/publication/361684853_A_new_endemic_species_of_pelvic-brooding_ricefish_Beloniformes_Adrianichthyidae_Oryzias_from_Lake_Kalimpa’a_Sulawesi_Indonesia

SHOAL released their annual report New Species 2022 on World Wildlife Day, Friday 3rd March 2023. The report details the 201 species of freshwater fish identified in 2022.

“What I most enjoy is getting a deeper appreciation for how evolution has proceeded. In order to really understand how things are evolving, you need to know who’s there, how many there are, you need to know what they’re doing.”

Christine Thacker is the Curator Emeritus of Ichthyology, Natural History Museum of Los Angeles County, and Research Associate, Santa Barbara Museum of Natural History. Her research concerns the evolution, systematics, and biogeography of gobies and cardinalfishes. She established the evolutionary relationships of this diverse radiation, yielding new family and lineage level classifications for the group1.

In 2022, she described six species of goby, two of which were from New Zealand, and four from Australia, which are highlighted in New Species 2022.

SHOAL: What do you love so much about gobies?

CHRISTINE: Gobies are so wonderful! They are so important in ecosystems, and are found around the world in all kinds of different habitats and it’s just fascinating because they exhibit such a wide range of evolutionary strategies. The new genomics tools that are coming out are opening up a whole new frontier.

SHOAL: What kind of new frontier are genomics tools opening up?

CHRISTINE: The thing about gobies is that they are in many cases morphologically sort of uniform – not entirely, obviously, but there’s not the range of variation that’s seen in the tunas or the flatfishes or things that are larger and much easier to work with in terms of their morphological data, i.e. their appearance. Gobies are small and yet they have so many important differences in terms of how they adapt to their environment and how they evolve, the way they speciate, that it’s been incredibly useful to use molecular tools to get at what’s going on. A lot of the time it can’t be seen just from the external appearance.

SHOAL: Taxonomy and describing species is very technical. What exactly is the process?

CHRISTINE: The first thing is that something is found, captured and examined and people think it is unusual and wonder, ‘Is this a new species?’. From that initial curiosity, you look at it very carefully, the morphology, the external appearance, the scales, the fin rays, the colour, the way the tail is shaped, the mouth, the teeth maybe and any ecological information you may have – where does it live, what does it eat, how does it reproduce – and then compare it to other species that are related to it to try and determine if this is really new.

And if it’s really different, either in appearance or behaviour or genetics, then the next step is to determine if the differences are really consistent. So, for instance you could look at some fish and say, ‘These red ones are different from these green ones,’ but if you find out that the red ones are sometimes half green or the green ones are sometimes a bit reddish, maybe that’s an indication that the red population is not actually a distinct species.

Once you think it’s new, the next step is to determine if there’s a name already assigned. And this is the paperwork part, the library research. You reach out to your colleagues, you look at field guides, at whether this has been treated by somebody else, as it’s entirely possible that somebody else knows this and named it years ago or in some other context.

You then write a paper that includes what it looks like, how it can be distinguished from its relatives, what the name is going to be, where the name comes from, what it means, and then crucially you want to provide as much information about this species as you can so that others can identify it.

It’s customary in a description to include photographs, drawings, tables, and any other information that will aid others in identifying it.

You also crucially have to deposit a type specimen: choose an individual that is representative of a species, that is preserved well, and then deposit it in a museum so that it is publicly available. There are rules about making type species available by others and making the paper published in an accessible form – other people need to be able to access it and use it.

SHOAL: What do you most enjoy about discovering and describing new species?

CHRISTINE: I think what I most enjoy about it is getting a deeper appreciation for how evolution has proceeded. In order to really understand how things are evolving, what they are doing, you need to know who’s there, how many there are, you need to know what they’re doing. That’s sort of the foundation for any further ecological evolutionary behavioural studies.

SHOAL: From the species that you described last year, is there one that is a standout to you?

CHRISTINE: I would say the bald carp gudgeon (Hypseleotris gymnocephala) is the most interesting. It has a very restricted parental distribution, and we didn’t think that we were going to find it. Peter Unmack found it in a little stream in New South Wales, Australia and it is genetically a beautiful little fish. They don’t have any scales on their heads, have tiny little faces and they have established a hybrid lineage that is incredibly widespread. They outcompete their parents. The question is, what is it about those hybrids that allow them to do better than their parents? They must have some incredible hybrid vigour. ‘Gymnocephala’ means ‘naked head’, as it doesn’t have scales on its head like most of the other taxa.

SHOAL: Is there anything else you’d like to add?

CHRISTINE: I would say the bald carp gudgeon (Hypseleotris gymnocephala) is the most interesting. It has a very restricted parental distribution, and we didn’t think that we were going to find it. Peter Unmack found it in a little stream in New South Wales, Australia and it is genetically a beautiful little fish. They don’t have any scales on their heads, have tiny little faces and they have established a hybrid lineage that is incredibly widespread. They outcompete their parents. The question is, what is it about those hybrids that allow them to do better than their parents? They must have some incredible hybrid vigour. ‘Gymnocephala’ means ‘naked head’, as it doesn’t have scales on its head like most of the other taxa.

1 https://nhm.org/person/thacker-christine

SHOAL released their annual report New Species 2022 on World Wildlife Day, Friday 3rd March 2023. The report details the 201 species of freshwater fish identified in 2022.

“Discovering and describing new species completes our knowledge about the diversity of life on Earth.”

Roberto Esser dos Reis, is a Brazilian ichthyologist, professor and Curator of Fishes at the Pontifical Catholic University of Rio Grande do Sul. With his students and collaborators, he has described 151 new taxa (including 139 new species), 17 new genera, and one new subfamily of fish.

In 2022 alone, he described eight species and one genus of freshwater fish, which are highlighted in New Species 2022. He also discovered a further six freshwater fish species that will likely be described over the coming years.

What do you most enjoy about discovering and describing species?

ROBERTO: What moves me is revealing undetected biodiversity and studying their phylogenetic relationships. Discovering and describing new species completes our knowledge about the diversity of life on Earth and allows for adequate conservation planning. Revealing their phylogenetic relationships – the part I like the most – uncovers the diversification of the group and brings to light explanations on evolution, biogeography and phylogeography of organisms.

Can you talk about the process of describing a species?

ROBERTO: This is not a simple process. It usually takes many years of detailed study of a museum or other biodiversity collection, careful fieldwork, and lots of reading of specialised literature.

Once you have the expertise, you must compare newly collected specimens (or those residing in a collection) with type-specimens (those previously used to describe species) and published descriptions. Then you will be able to find the subtle differences that can tell independent evolutionary lineages (i.e. species) apart.

In the last 20 or so years, the possibility of using DNA segments to help this process has improved our ability to detect such lineages and demonstrate they are evolving independently. This is the process of discovering undescribed diversity. Describing and publishing is a much simpler process that also requires some expertise and training. I am proud of having trained many grad students in both parts of the process.

Can you talk through a particularly memorable species discovery?

ROBERTO: Back in 2003 I was conducting fieldwork in the Ucayali River in Peru, and I knew from European aquarium magazines of a new species of Otocinclus (a small suckermouth catfish) from that region. I spent around two weeks looking for this and other fishes and could not find it. At the end of the expedition, I was with my team at the harbor in Jenaro Herrera to take the boat back to Iquitos, and suddenly a local fish collector for the aquarium trade arrived at the harbor with dozens of flat, wooden trays coated with plastic, obviously carrying ornamental fishes to sell to the aquarium fish exporters in Iquitos. I asked permission and started peeking at each tray and eventually found one full of the new Otocinclus I was looking for! They were collected in a nearby creek and lake which I was not aware of! I then purchased some 30 specimens from the fisher, preserved them during the boat trip, and used those specimens to describe Otocinclus Cocama – a very beautiful fish!

Are there any characteristics of a place that make it more likely to have undescribed or undiscovered species living there?

ROBERTO: Well, this is a tricky question. Obviously, I would expect unexplored areas (like the eastern Amazon, or the southern Orinoco basin) to have more unknown species. This is generally true. However, I can show you several papers, some by myself, describing new species from areas heavily sampled during the last 200 years!

At this very moment I am conducting a study describing five new species of another group of suckermouth catfish from the upper Uruguay River in south Brazil, an area that my team have collected heavily for about 30 years. Most of the fishes were already pickled and sitting on a shelf in our own museum, but are so far undetected as undescribed. It’s a matter of being able to detect them.

Can you estimate how many species may yet be discovered and described in South America, and the world?

ROBERTO: Fish is a big group with about 36,400 species today. Approximately half are freshwater and half are marine. In the last 20 years or so, an average of 104 new species are described for the Neotropical region alone. In 2016 I published with colleagues an article showing that we had in South America some 5,160 freshwater fish species, and we estimated a final diversity between 8,000 and 9,000 species.

Sturisoma reisi, one of the notable species in this report, was named after you. Are there other species named after you?

ROBERTO: Yes! A former PhD student described Sturisoma reisi in my honor. As well as that, there is Ancistrus reisi, Phalloceros reisi, Rineloricaria reisi, Scleromystax reisi, and Brachychalcinus reisi. Sturisoma reisi is a very beautiful fish, from the Guaporé River, Madeira River basin, and collected near Costa Marques in the state of Rondônia, Brazil. It’s a really cool fish that lives, as most other suckermouth catfishes, in the bottom of swift creeks and rivers. This particular species can be found more commonly on logs and tree branches fallen into the water.

SHOAL released their annual report New Species 2022 on World Wildlife Day, Friday 3rd March 2023. The report details the 201 species of freshwater fish identified in 2022.