Fishes of Amazon's Last Frontiers

Latest update January 31, 2019 Started on August 26, 2018

A series of expeditions to find, collect, and study fishes in poorly explored or unexplored areas of the Amazon basin before they disappear

August 26, 2018
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In The Field

Day 7-17: Coppename River – Part 3

Tetras (Picture), catfishes, cichlids, electric fishes, stingrays, and water for environmental DNA (eDNA) were collected in the clear waters of the Coppename River (Video). We identified more than 100 species in the rapids at the Grand Island and in surrounds streams.

Many of the species captured in the Coppename River are new to science, representing new occurrences to the locality, or are topotypes (species described at the Coppename River way before our expedition). All collected material will be deposited in the Muséum d’Histoire Naturelle Genève, National Museum of Natural History – Simithsonian Institution, Museu de Zoologia da Universidade São Paulo and used in studies about diversity, evolution, and ecology.

As for instance, information on 17 electric eels caught during the expedition, will be used in two folds. First, investigating species diversity in the electric eel, and it position in the fish tree of life. Second, studying electric eel ecology and behavior - My PhD student, Douglas Bastos, is working on the natural history of the electric eel. Thus, observations made during the trip will be useful for him to understand the way of life of electric eels.

Likewise, the water samples collected for eDNA, will help us to determine the efficacy of eDNA in detect the Neotropical megadiverse fish fauna (estimated in over 5,300 species). Free molecules of DNA are spread in the water as in losing scales, excrements and secretions. eDNA can detect numerous species of organisms as fishes, via a sample of water. This recently created, non-invasive, sampling method has emerged as a complementary, and possible substitute to invasive methods in a near future, to take biodiversity surveys, improve species distribution and monitoring aquatic systems.

After the 10 days of intensive work at the Coppename River we were tired, but very happy with the partial results of the expedition (Picture - from L to R Charles Henry, Raph Covain, Elmond, Kenneth Wan, Luiz Peixoto & Michel Gianeti), which will help us to understand the origin of Guianese fishes.

The last stop of the expedition will take us to the Corantijn River in the border between Suriname and Guyana.

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Day 7-17: Coppename River – Part 2

We arrived in Witagron or Bitagron, located in the district of Sipaliwni at the margin of the Coppename River, after having driven for more than five hours from Paramaribo. In Witagron, we met our new crew of helpers that included two boatmen and one cook for a journey by boat up river through the Coppename rapids where we camped for 10 days.

Soon enough we learned that the horrifying noises heard early that morning were produced by groups of howler monkeys (more information at Different groups would start “Howling” at 2 am and continue until 6-7 am! After the fog faded away into the deep green forest along the Coppename River, we could appreciate the astonishing scene at Grand Island and get ready to sample (Watch video).

The Coppename River, particularly at the Grand Island, had clear waters allowing us to spot hundreds of tetras, piranhas, cichlids, and catfishes swimming among the rocks in the rapids. Now familiarized with the fish finder, Luiz and Michel did not waste time and went straight to explore the surroundings of the island. Quickly they discovered that the Coppename River was also house for a number of species of electric fishes, including the world-celebrated electric eel, hiding in the sand or into rocks crevices.

After recognizing the surroundings we started preparing to sample the locality. Combining sampling and identifying approaches is critical to obtain a comprehensive picture of biodiversity. Thus, we used two sampling methods: capture-based and molecular-based. The former approach utilizes fishing nets, such as hand nets and caste nets, to capture fishes. The latter methodology, popularly known as environmental DNA sampling, allows us to detect the fishes that live in a certain area by collecting samples of the water and analyzing its genetic content.

To be continued…

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Day 7-17: Coppename River - Part 1

After an over seven hours journey we docked in the middle of the night at Grand Island in the Coppename River (Photos). Following to partially camping set we were ready to rest.

Early next morning we were woke up by a loud and frightening sound coming from a foggy forest! Many of us were wondering, what was going on? Which kind of animal was capable to produce such a terrifying noise (play the video!)? Wild pigs? Monkeys? Birds?

To be continued…

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Day 3-5: Suriname River – Part 3

We were collecting tetras, Corydoras, plecos, cichlids and piranhas in the creek when Michel Gianeti and Luiz Peixoto heard a buzzing sound coming from sand and leaf litter via a fish finder.

South American electric knifefishes (Order Gymnotiformes) are group of 250+ species that inhabit freshwaters and can generate electricity using at least one electric organ.

Among others fishes, this group includes the world celebrate electric eel (Electrophorus electricus) and black ghost knifefish (Apteronotus albifrons) - popular in the aquarium trade.

That was the first time that Luiz and Michel used a fish detector. They were very excited with the different sounds that could be heard through the speaker.

All South American electric knifefishes produce weak electric organ discharges – EODs –ranging from 10Hz to 2000Hz, used to navigation and communication.

The electric organs consist of modified muscle or nerve cells known as electrocytes (comparable to small batteries). When firing, via a simultaneous command from the brain, electrocytes acting as serially connected batteries.

EODs are divided in two types: pulse and wave.

Pulses EODs are brief all-or-none events of the order of 1 ms or a few milliseconds separated by much longer intervals. Heard with the fish finder, a buzzing sound or single clicks at very low discharge rates are heard.

Wave EODs have no pauses between them, thus that they represent a continuous wave and are of a constant frequency that may be modulated when the fish is excited. Heard with the fish finder, wave EODs sound like a musical instrument playing a constant tone.

The only South American freshwater fish capable of give you a shock is the electric eel. In addition to weak EODs, the electric eel produce strong EODs up to 650V for hunting and self-defense.

The electric eel possess three electric organs: Main, Hunter’s and Sachs. Main and Hunter’s electric organs produce high voltage EODs and Sachs generates the low-voltage pulse EODs.

For more information on electric fishes go to

Soon enough with a hand net Luiz and Michel discovered the buzzing sound was produced by species of bluntnose knifefish Hypopomus artedi (biggest fish in the video) and banded knifefish Gymnotus coropinae (smallest fish in the video and in the picture by D. Bastos).

Unfortunately, we found an enormous amount of bottles, bags and waste floating in the Suriname River, probably, coming from near by communities. Recently, plastic particles were found in the stomach content of Amazonian fishes. Sadly, it could be one more example of plastic pollution affecting wildlife.

The fishes captured in the Suriname River will help us to understand the origin of the diversity of fishes in Guianas.

The number of fishes sampled in the Suriname River was lower than expected. After three days in the Suriname River and having caught ca. 50 species of fishes, we returned to Paramaribo, to buy more supplies and prepare for a long trip to the Coppename River in the heart of the country.

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Awesome David ! We are following you!

Hope you like our expedition: "Brazilian Marine Parks"

Day 3-5: Suriname River – Part 2

The fish detector - consists of a differential amplifier connected to a dipole connector associated to a microphone cable. It amplifies electric fish discharges from an underwater electrode and translates them into sound passing through a speaker.

By using a fish detector we can easily localize, and then collect electric fishes (Photo by M. Gianeti. The author-left & Luiz Peixoto collecting electric fishes).

Also check my posts at

To be continued….


It did not take long, and we arrived at the rapids at Bakaaboto in Sipaliwini district after two hours on the road.

Rapids and falls are usually underexplored and highly endanger environments - due the constructions of hydroelectric dams in South American rivers. These stony or gravel bottom environments (Photos. Aerial views of rapids at Bakaaboto) are home for a unique group of fishes adapted to life in oxygen rich and high-energy waters (including catfishes, Characiformes, electric fishes, and cichlids), the so-called rheophilic fishes (Photo. Leporinus faciatus - two banded individuals; Moenkhausia surinamensis)

The Suriname River is nearly 500 km long and flows from south from its source in the Guiana highlands to north into the Atlantic ocean. It is the more important river in the country being home of main harbors to import and export goods. Likewise, this river is a significant landmark for scientists that study Neotropical fishes. Since, it is the type locality for a number of species described in the eighteenth-century by Swedish naturalist Carl Linnaeus. This means that the Suriname River as well other rivers are the type locality for species described way before our expedition. As for the mustang cactus pleco catfish, Pseudacanthicus serratus, described by the French zoologist Achille Valenciennes in 1840 (Photo. Raphaël Covain holding a specimen of P. serratus).

Collecting in the type localities is particularly important for recognizing and/ or delimiting widespread species. For instance, populations from the type locality can be compared with those form other locations that live throughout the distributional range of a species. As a result, populations outside the type locality will either continue to be classified as the same species, or may have their taxonomic status change, i.e. be recognized as a different species; in many cases these are undescribed species).

Creeks also have a distinctive fish fauna, and exploration of these environments with a fish detector can reveal a secret world inhabited by electric fishes.


To be continued…..

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Day 1 & 2: After a 120 minute’s flight we landed in a fog morning in Paramaribo. The short distance, 683 miles, between Belém and Paramaribo hide from view the huge cultural diversity of the Suriname.

The formerly known Dutch Guiana, the Suriname initially colonized by the British, and then acquired by the Dutch, obtained its independence in 1975.

It is limited to the west by Guyana, to east by French Guiana, to north by the Atlantic Ocean, and to south by Brazil.

The right-hand car waiting for us at Johan Adolf Pengel International Airport, located 45km from Paramaribo was the signal of British occupation in Suriname. From a plantation economy in the eighteenth-century to bauxite, gold, and oil directed Nation in the twenty and twenty-first centuries, the Suriname is home for an incredible ethic diverse population of ca. 560.000 people.

Dutch is the official and common language among the diverse ethnicities that learn it as a second idiom. In addition, a number of Creole dialects can be heard in the busy streets and public markets (Photo) of Paramaribo being the Taki-Taki (Sranan Togo) the most common.

Indian descendants are the largest ethnic group in Suriname with 27%, followed by descendants of escaped slaves of African origin, the Maroons with 21%. Another representative ethnic group are the Afro-Surinamese, Creoles with 17%. Equally representative are the descendants of Javanese and people of mixed ethnicity, both with roughly 13% of the population. The native Surinamese people include 8% of the population.

The first two days in Paramaribo were used to meet our hosts Jan Mol and Ken Wan Tong You from the Anton de Kom University of Suriname, assembling our international team of scientists and citizen scientists (Photo - From left to the right Michel Gianeti, Raphael Covain, Jan Mol, me - C. David de Santana, Charles-Henri Eon, and Luiz Peixoto), buying extra supplies, and testing all the equipments before getting in the road towards the rapids of the Suriname River (Photo).

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Suriname Expedition

In Belém (photo), Brazil, waiting for my flight to Suriname!

Sponsored by Smithsonian’s Global Genome Initiative, FAPESP/Smithsonian Institution (#2016/190759), DNA Barcode Network, OpenROV, and in partnership with Deep Trekker this international expedition (Smithsonian’s National Museum of Natural History, Muséum d'Histoire Naturelle Geneve, Museu de Zoologia da Universidade de São Paulo, and Anton de Kom University of Suriname) will explore and collect fishes in largely unknown portion of the Coppename, Corantijn and Suriname rivers (see map)!

Stay tuned for new posts!!!

For more information on my research visit:

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Our next expedition will begins in late October of 2018 in a distant and largely unknown portion of the Coppename and Corantijn Rivers in Suriname.

In meanwhile, enjoy the account of our first adventure into the Javari Valley in Brazil.

Javari River*

Sponsored by a grant from the São Paulo State Research Foundation (FAPESP #2016/07910-0) to Gislene Torrente-Vilara, and a Global Genome Initiative grant to me (GGI-Peer-2017-149), the Javari expedition took place in the fall of 2017 with a joint team of preeminent field ichthyologists, led by Gislene Vilara, including Douglas Bastos, Jansen Zuanon, Shizuka Hashimoto from INPA; Ariana Ribeiro from Universidade Federal de Rondonia; Felipe Rocha from UNIFESP and myself. Completing our team were experienced fishermen as Roberval Ribeiro, guides and cooks.

We embarked on the “Água Viva” vessel on an extraordinary voyage to explore the white waters of the Javari River in Brazil (Figure 1 - team & vessel by D. Bastos).

This area, larger than South Carolina, houses one of the biggest indigenous territories in Brazil (>3,000 native Brazilians) and the highest concentration of uncontacted tribes in the world. There, we sampled in different habitats for specimens, tissues, and water for environmental DNA (eDNA) for more than three weeks.

Various fishing approaches were used including trawl nets in the river channels, seine nets in the beaches, hand nets in streams, cast nets in rapids. We collected thousands of specimens, and tissue samples were extracted for 450+ species of fishes (Figure 2 - 12 cm long South American leaf fish by D. Bastos). The specimens were deposited at the fish collection at INPA and tissues and extracted DNA at the Smithsonian, Instituto Nacional de Pesquisas da Amazônia (INPA), and Museu de Zoologia de São Paulo Biorepositories.

In addition, Douglas Bastos (Figure 3), my PhD student at INPA, made in situ observations for his pioneer thesis on the natural history of the electric eel (genus Electrophorus).

Tissue samples will be used for building two genetic libraries: DNA barcoding and eDNA. DNA barcoding use a small portion of the fish’s DNA—obtained through a fin clip to identify the species. It will increase our accuracy in recognizing species in different life stages, and also species that can’t be easily identifiable based on their morphologies. Once completed, the eDNA library will be available to document species diversity present in the target habitat by simply sequencing the residual fish product contained in the water. Quite inexpensive when compared with traditional assessment methods, as well as accurate and non-invasive, analysis of eDNA will play an important role in biodiversity surveys and conservation studies in the near future.

Based on the collected specimens, the material was identified to species level in the field, and IDs were double checked at INPA. Results indicate that ~10% of the species captured are new to science.

The Javari River expedition was extremely successful and was the first step to accomplish our broader aims of exploring, collecting and studying fishes in the Amazon's last frontiers.

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Expedition Background

Fishes represent the most diverse groups of vertebrates with ~33,700 species. Remarkably ~15,000 of species inhabit freshwaters, which covers only 2% of Earth’s surface! Thousands more species remain to be described.

The Amazon is one of 25 recognized biodiversity hotspots and, along with the Congo in Africa and aquatic habitats in South East Asia, is one of three big rainforests left in the world. The Amazon maintains the most diverse riverine ichthyofauna on Earth with over 3,000 species.

The origin of those fishes dates at least to the separation between Africa and South America (~110 million years before present). As such the living Amazonian fishes reflect a long history of geological and biological isolation. Likewise, rivers in South America mirror the soil geology they pass through and are classified according to the color of their waters: white (e.g., Amazon River), clear (e.g., Xingu River) and black (e.g., Rio Negro).

The Amazon basin is also one of the most vulnerable environments on Earth. Human impacts in the Amazon accelerated after 1950, and have included the construction of hydroelectric power plants and an increase in mining activities. At this pace we predict that countless numbers of organisms are already, or are in imminent danger of becoming, extinct even before we known them.

For that reason, the Division Fishes at the National Museum of Natural History (NMNH; Lynne Parenti and I), Global Genome Initiative (GGI) and the DNA Barcode Network of the Smithsonian Institution are working together with the Museu de Zoologia da Universidade de São Paulo (MZUSP; Naércio Menezes, Aléssio Datovo, and Osvaldo Oyakawa), Instituto Nacional de Pesquisas da Amazônia (INPA; Jansen Zuanon), Universidade Federal de São Paulo (UNIFESP; Gislene Vilara), Cornell University (CU; Casey Dillman), and Musée D'Histoire Naturelle de Suisse (Raphaël Covain) to find, collect, and study fishes in the last frontiers of the Greater Amazonia (a superbasin comprising the Amazon, Orinoco, and coastal drainages of the Guianas).

I am C. David de Santana, Research Associate in the Division of Fishes at the NMNH. As a zoologist my work focuses on describing and understanding freshwater fish diversity.

My interest in fish dates back to my childhood. As a youngster, I was curious about their behavior in aquarium. As I grew older, I was attracted by the huge diversity of fishes and decided to fill the gap in the knowledge of diversity studying electric fishes (a group of 250+ species of freshwater fishes of the order Gymnotiformes that can produce electricity through at least one electric organ). Since then, I have discovered more than 130 new species of electric fishes, 80 of which were described.

Starting herein, I will share with the Open Explorer Community a series of adventures to distant and largely unknown portions of the Amazon basin! During our journeys I will take you throughout rapids, river channels, lakes and streams searching for fish diversity and introduce you to the world of electric fishes.


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