The Vaupés River stands out as one of the few within the Amazon basin due to its numerous rapids. These riverine fast-flowing sections not only provide habitat to highly specialized fishes but also function as natural barriers hindering the movement of fish along its course. During a fish-collecting expedition in the lower Vaupés River basin in Colombia, 95 species were registered belonging to 30 families and seven orders. Despite recent inventories in the region, our comprehensive sampling efforts particularly focused on the rapids and associated rheophilic fauna, allowing us to contribute the first records of four fish species in Colombia (Myloplus lucienae Andrade, Ota, Bastos & Jégu, 2016, Tometes makue Jégu, Santos & Jégu, 2002, also first record of the genus, Leptodoras praelongus (Myers & Weitzman, 1956), and Eigenmannia matintapereira Peixoto, Dutra & Wosiacki, 2015) and six presumably undescribed species (i.e., Jupiaba sp., Moenkhausia sp., Phenacogaster sp., Bunocephalus sp., Hemiancistrus sp., and Archolaemus sp.). In this study, a commented list of the ichthyofauna of these environments is presented, as well as a photographic catalog of fish species integrated into the CaVFish Project – Colombia.

Conservation, freshwater, Neotropical fishes, new records, PhotaFish System, range expansion, taxonomy

The Neotropical Region is the biogeographic region with the highest number of freshwater fish species globally, and recent estimates suggest approximately 9,000 species (Reis et al. 2016; Birindelli and Sidlauskas 2018; Dagosta and de Pinna 2019). Some localities in the Amazon River basin often exhibit remarkably high fish species richness that surpasses the hundreds (Albert and Reis 2011). The extraordinary radiation of fishes that occurred in the Neotropical region is often explained as the product of geographic events over extended geological periods (Albert and Crampton 2010; Albert and Reis 2011; Albert et al. 2020), but also lineage diversification related to habitat utilization and trophic specialization (Lujan et al. 2012; Lujan and Conway 2015; Arbour and López-Fernández 2016; Roxo et al. 2017; Kolmann et al. 2021).The Vaupés River and its fish have a long history of expeditions that began in the 18^th and 19^th centuries by early naturalists, such as Alexandre Rodrigues Ferreira, Alexander Von Humboldt, and Alfred Russel Wallace (Lima et al. 2005). Recent analyses of fish biodiversity and hotspots in Amazonia suggested that the Vaupés hydrographic basin in its entirety has high values of species richness and endemism (Jézéquel et al. 2020a), species with high levels of irreplaceability, representativeness, and degree of vulnerability (Jézéquel et al. 2020b). Unlike other tributaries of the Amazon, the numerous rapids of the Vaupés River serve as habitat and provide food (e.g., Podostemaceae aquatic plants) for fish (Lima et al. 2005); in addition, rapids act as natural barriers that affect the dispersal of some fish and harbor rheophilic and endemic fish species (Londoño-Burbano and Urbano-Bonilla 2018; Urbano-Bonilla et al. 2023).

The River Negro Basin, of which Vaupés River is a major tributary, has a rich ichthyofauna, with 1,165 species known to science. A large portion of these species are shared with adjacent basins (i.e., Orinoco), but ~ 15% are endemic (156 species; Beltrão et al. 2019). The western Rio Negro tributaries are known for their distinctive rheophilic fish fauna (Lima et al. 2005). A total of 224 fish species are known to occur in the Vaupés River in Colombia (Bogotá-Gregory et al. 2020, 2022a); some of these species are endemic to this basin, while others are widely distributed in the Amazon basin and adjacent basins such as the Orinoco and those within the Guiana Shield (van der Sleen and Albert 2017; Beltrão et al. 2019; Bogotá-Gregory et al. 2020, 2022a, 2022b; Taphorn et al. 2022).

Despite historic and contemporary sampling efforts, the Vaupés River remains largely under-sampled mainly because of its remote geographical location and numerous rapids, preventing access and navigation. Also, after putting an end to a 60-year conflict between the Colombian state and one of the oldest guerrilla organizations in the world (Fuerzas Armadas Revolucionarias de Colombia-Ejército del Pueblo FARC-EP), biological expeditions were carried out filling an important information gap relative to this previously unreachable area (Botero 2020; Irwin 2023). Recent studies evaluating the sampling efforts to inventory Amazon River basin ichthyofauna reveal that extensive areas in southwestern Colombia remain almost unsampled (Jézéquel et al. 2020a). Recent reviews purported new records for the basin and Colombia suggesting that the biodiversity knowledge of the area is still incipient (Bogotá-Gregory et al. 2020, 2022a).

Here we describe the results of an expedition to the lower Vaupés River basin with the goal of investigating fish species associated with the rapids and surrounding environments in the Vaupés arc (Miocene ≈ 10 Mya; see Fig. 1). Tragically during this expedition Colombian, in the Matapí Rapids in the Vaupés River, the boat transporting researchers capsized, and the leader of the expedition, ichthyologist Javier Maldonado-Ocampo passed away (read more in Urbano-Bonilla et al. 2021). This document is a tribute to the effort of Javier, who dedicated his life to the generation and transmission of knowledge aimed at recognizing the diversity of Colombian fishes and rescuing ancestral knowledge.

Figure 1. 

Location of the Vaupés River in Colombia and distribution of sampling sites along the lower Vaupés River. Key: pink triangle – Trubón Community Rapids; green triangle – Villa Fátima Community Rapids; red triangle – Nana Community Rapids; yellow triangle – Macucú Community Rapids; white triangle – Matapí Community Rapids, and blue triangle – military base.

The Amazon Basin has the greatest freshwater fish biodiversity on the planet (Tisseuil et al. 2013; Dagosta and de Pinna 2019). The Negro River basin and its main drainages have been explored for the last three centuries (Lima et al. 2005). Historical analyses (1821–2019), however, suggest that species richness in the Negro basin is far from being fully known, given that the rate of species descriptions has not stabilized (Beltrão et al. 2019) and there are still areas unexplored scientifically (Jézéquel et al. 2020a). In the Brazilian part of the basin, the uniqueness of the headwater ichthyofaunas are well-documented (Lima et al. 2005), resulting in recent descriptions of more than 30 new species (Beltrão et al. 2019; Bogotá-Gregory et al. 2022a). Recent rigorous work resulted in recording 1,165 fish species associated with different aquatic environments in the basin (Beltrão et al. 2019). Of this compilation, Bogotá-Gregory et al. (2022a) recorded 224 species in the middle Vaupés River basin, of which ten are new records for Colombia and 26 are new records for the Colombian Amazon basin. Our research in the lower Vaupés River basin adds four new records for Colombia and 44 new records (see Table 3) not included in Bogotá-Gregory et al. (2022a), resulting in 268 fish species now known in the middle and lower portions of the Vaupés River basin.

Based on these recent lists of fish species composition (Beltrão et al. 2019; Bogotá-Gregory et al. 2022a) and our results, the entire Negro River basin reaches an approximate richness of 1,210 species. This richness value is still under the predicted estimates that vary between 1,466 and 1,759 species (Beltrão et al. 2019). Despite this, our expedition revealed new records for Colombia, and undescribed species to science, demonstrating that fish diversity in the region is still far from completely known (Bogotá-Gregory et al. 2020).

Although the Vaupés drainages located to the southwest of our study area have been well sampled (rivers Papuri, Cuduyari Paca, Mituceño, and Tiquié), this study adds new records for the country. Therefore, it is essential to continue monitoring fishes from rheophilic environments and especially those that live in the headwaters of the Vaupés (e.g., Itilla and Unilla rivers; see Fig. 1). This area is recognized for its high degree of species endemism (Hernández-Camacho et al. 1992), the singularity of its fish fauna (Londoño-Burbano and Urbano-Bonilla 2018; Lima et al. 2020), and its connectivity with two protected natural area, the Serranías de la Macarena and Chiribiquete National Parks (Botero and Serrano 2019).

Two new records for Colombia are represented by the serrasalmids Myloplus lucienae and Tometes makue. From the expeditions of Alfred Russel Wallace (1850–1852) along the Vaupés River, there are illustrations of 43 specimens, representing ~ 40 serrasalmid species (Toledo-Piza 2002). Of these, the fish named “pacu-muritinga” and “pacu-tinga” came to be recognized as Myloplus lucienae, a species associated with both rapids and more slowly running waters (Andrade et al. 2016). Therefore, despite the long-known occurrence of this species downstream in the Negro River, this is the first record of this species upstream in the Colombian portion of this basin.

Before the present record of Myloplus lucienae in Colombia, the genus was represented by four species in the country, M. asterias (Müller & Troschel, 1844), M. rubripinnis (Müller & Troschel, 1844), M. schomburgkii (Jardine, 1841), and M. torquatus (Kner, 1858). The genus Tometes, however, was not yet recorded in Colombia (Bogotá-Gregory et al. 2022a; DoNascimiento et al. 2024). The populations of M. lucienae are distributed in the Negro River basin in Brazil (Andrade et al. 2016) and those of Tometes makue in the middle and upper basin of the Negro River in Brazil and the Orinoco River in Venezuela (Jégu et al. 2002); we now document for Colombia the sympatric occurrence of M. lucienae (Fig. 3A) and T. makue (Fig. 3B). These fishes live in rocky rapids preferably associated with habitats with abundant aquatic vegetation (Podostemaceae). Sympatric fish assemblages form through dispersal and ecological coexistence (Thomaz et al. 2019; Albert et al. 2020).

In T. makue, the stomach contents of adult specimens reveal that Podostemaceae plants represent a very important part of the diet of these fishes (Jégu et al. 2002; Lima et al. 2005). On the other hand, Mylopus species are generalist herbivorous, with seeds as the main food source, and occasionally feeding on small aquatic animals (van der Sleen and Albert 2017; Correa and Winemiller 2018). In an analysis of the evolution of the diet in the Serrasalmidae family, associated changes in dentition highlight ecomorphological diversity (Kolmann et al. 2021). Podostemaceae makes up most of the diet (based on relative volume) of Tometes compared with Mylopus (Kolmann et al. 2021), which may explain their sympatric existence.

Between 1923 and 1925 ichthyologist Dr. Carl Ternetz traveled the Amazon from Manaus, up the Negro River and across to the Orinoco River, accruing collections that resulted in descriptions of several new species (Lima et al. 2005). During this expedition, the collected specimens of a fish would be described as Hassar praelongus Myers & Weitzman, 1956 (currently Leptodoras praelongus) 38 years later, distributed in Brazil and Venezuela (Sabaj 2005; Beltrão et al. 2019). Species of the genus Leptodoras are widely distributed in the Amazon, Orinoco and Essequibo River basins (Sabaj 2005; Birindelli et al. 2008; van der Sleen and Albert 2017; Taphorn et al. 2022). In the Negro River basin (Brazil), seven species [(Leptodoras acipenserinus (Günther, 1868), L. cataniai Sabaj Pérez, 2005, L. copei (Fernández-Yépez, 1968), L. hasemani (Steindachner, 1915), L. juruensis Boulenger, 1898, L. linnelli Eigenmann, 1912, and L. praelongus (Myers & Weitzman, 1956)] are known (Beltrão et al. 2019) while for the entire Colombian Amazon five species are known [(L. acipenserinus, L. copei, L. juruensis, L. linnelli, and L. myersi Böhlke, 1970; Bogotá-Gregory et al. 2022a; DoNascimiento et al. 2024)]. Of these, four are shared with drainages of the Colombian Amazon and the Negro River (L. acipenserinus, L. copei, L. juruensis, and L. linnelli); two species live in this last river (L. cataniai and L. hasemani) that are absent in the Colombian Amazon, and that does have records of L. myersi, currently absent in the Negro River (Beltrão et al. 2019; DoNascimiento et al. 2024). In the rapids of the Macucú community (Mitú), a single specimen of Leptodoras praelongus (Fig. 3C) was collected from benthic habitats in deep, fast flowing waters. Some species in the genus (e.g., L. juruensis and L. myersi) are restricted to deep habitats (50 m; Sabaj 2005). Leptodoras praelongus possibly lives in sympatry with L. copei, recorded for the middle Vaupés River basin (Bogotá-Gregory et al. 2022a), contrasting with L. cf. linnelli that lives downstream in the rapids of Carurú, at the border between Brazil and Colombia (Lima et al. 2005).

Within the electric glassfishes, we recorded new species for Colombia in the genus Eigenmannia Jordan & Evermann, 1896. This genus represents the most diverse group in the family Sternopygidae and is distributed throughout Central and South America (Fricke et al. 2023), with its greatest diversity in the Amazon basin (Peixoto and Ohara 2019). It has 24 valid species distributed into two groups; one is called E. trilineata group, which includes 22 species (Dutra et al. 2022), with a complex taxonomy, and until recently, E. virescens (Valenciennes, 1836) and E. trilineata López & Castello, 1966 were erroneously cited as occurring in several Amazon basin drainages. We indicate the presence of two species belonging to the E. trilineata group: E. matintapereira and an unidentified species. Although there are specimens identified as Eigenmannia sp. in other recent inventories in the region (Lima et al. 2005: 256; Bogotá-Gregory et al. 2022a), it is difficult to confirm if these species belong to E. matintapereira or even the E. trilineata group. Despite that, the present study highlights the sympatry of at least two morphotypes of Eigenmannia that occur in the lower basin of the Vaupés River associated with rocky rapids and sandy beaches.

Oberdorff et al. (2019) evaluated 97 Amazon basin drainages and found the size of the habitat, the modern and past climates, and isolation due to natural waterfalls contribute to explain patterns of endemic richness. Naturally, the Vaupés River and the breaks in the relief represented by numerous rapids are common in some of its main drainages. An example of this is the Tiquié River, a tributary of the Vaupés (Fig. 1), which in its route through the different rapids (i.e., Pari-Cachoeira, Pedra Curta, Comprida, and Carurú) shows gradients in fish communities in the downstream-upstream direction; upstream of the Carurú rapids, the absence of some genera (Phenacogaster Eigenmann, 1907 and Serrasalmus Lacepède, 1803) or species [(Moenkhausia collettii (Steindachner, 1882), Anduzedoras oxyrhynchus (Valenciennes, 1821), Pseudoplatystoma tigrinum (Valenciennes, 1840), Ageneiosus inermis (Linnaeus, 1766)] (Lima et al. 2005) is evident. This seems to be consistent with our results, with the exception of A. inermis, which is one of the 92 species of fish identified by the inhabitants of the Tiquié communities in Colombia (Campuzano-Zuluaga 2019).

Contrary to what was observed in the upper part of the Tiquié River, the rapids of the Vaupés River in Colombia (e.g., Fig. 1: rapids upstream between the Colombia-Brazil border to the town of Mitú: Carurú, Matapí, Tapira Geral, La Mojarra, Macucú, Nana, Villa Fátima rapids) present a different pattern in the occurrence of species since most species listed above are also found in this part of the drainage. In this sense, the rapids at the headwaters of the Vaupes River possibly act as dispersal filters for some species of fishes.

Records are located in the Vaupés Arc, a Miocene origin arch that represents the divide between the Amazon-Orinoco river basins, and represents a semi-permeable barrier for fish dispersal (Winemiler and Willis 2011: table 14.3). Anecdotally, local communities refer to an absence of species upstream of the rapids of Carurú (1°5'8.81"N, 69°19'39"W) that constitutes an important barrier for fish dispersal. An example is the absence of freshwater stingrays Potamotrygon Garman, 1877), the electric eel (Electrophorus Gill, 1864), and large migratory catfish (Brachyplatystoma Bleeker, 1862) as evidenced in Table 3 and previously published lists of the middle Vaupés River basin in Colombia (Bogotá‐Gregory et al. 2022a). In our expedition, we sampled only upstream of this barrier and we did not collect any of these groups.

From another territorial perspective, the historical and traditional knowledge of indigenous communities makes it possible to identify the anthropic displacement of species for subsistence purposes in the Amazon basin (Lima et al. 2005; Camacho-García 2013; Campuzano-Zuluaga 2019). In 1950, in the upper Tiquié River basin, the community transported upstream of the Pedra Curta rapids a fish for consumption, Satanoperca jurupari (Heckel, 1840), and it was anticipated that it would colonize the headwaters of the river on the Colombian side (Lima et al. 2005). The coexistence of this species with locally native fish was confirmed 14 years later (Campuzano-Zuluaga, 2019). In addition, it was known that this species was already found naturally in the middle basin of the Vaupés (Bogotá-Gregory et al. 2022a) including its headwaters, i.e., the Unilla and Itilla rivers (Prada-Pedreros et al. 2018). Likewise, in 1990 another fish used by the communities, Lugubria johanna (Heckel, 1840) was transported from the Japurá-Caquetá River basin (in Brazil) to the headwaters of the Tiquié (on the Colombian side) (Lima et al. 2005; Campuzano-Zuluaga 2019) and today inhabits the entire Vaupés River basin, including the main channel, lagoons and main drainages (Beltrão et al. 2019).

Transporting fish species among subbasins of the upper Vaupés River in Colombia threatens both the aquatic biodiversity and the fisheries production of this region. The historical and traditional records reveal the introduction of non-native species, mostly cichlids [(e.g., Lugubria johanna, Heros sp., Mesonauta insignis (Heckel, 1840), Satanoperca jurupari)] and an Erythrinidae (Hoplias lacerdae Ribeiro, 1908) in the upper Tiquié (Lima et al. 2005; Campuzano-Zuluaga, 2019) that could be related to the decline in the populations of the region’s native fish fauna, and threaten the security and food security of the peoples present there (Campuzano-Zuluaga, 2019). Although these species are widely distributed in the Amazon, Orinoco, and Guyanese Shield basins (Beltrão et al. 2019), historical data show translocation of these fish in areas where they did not occur before, and isolated to a certain extent by a series of rapids but living in sympatry with natural populations (Lima et al. 2005).

Regarding cichlids, an example of the extinction of the endemic fauna is known when Lates niloticus (Linnaeus, 1758) was introduced to Lake Victoria (Witte et al. 1992). Species checklists and photos document the composition of fish (native and non-native) of the upper Tiquié River, which rises in the southeast of the Colombian territory, in a lagoon system called Ewura (Campuzano-Zuluaga 2019), on its way through Brazilian territory they give way to countless rapids that can act as barriers (Lima et al. 2005). In recent years, endemic (native) fish species have recently been discovered from specific areas of the Tiquié River basin in Brazil [(e.g., Corydoras desana Lima & Sazima, 2017; Hypostomus kopeyaka and H. weberi Carvalho, Lima & Zawadzki, 2010, Rhinotocinclus yaka (Lehmann A., Lima & Reis, 2018)] and from the Vaupés River in Colombia (i.e., Rineloricaria jurupari Londoño-Burbano & Urbano-Bonilla, 2018, Hemigrammus xaveriellus Lima, Urbano-Bonilla, Prada-Pedreros, 2020 and Rineloricaria cachivera Urbano-Bonilla, Londoño-Burbano & Carvalho, 2023). The introduction of non-native fish such as Cichlids generates irreversible effects (displacement, extinction of species, and loss of the gene pool of native species) due to (intraspecific) competition and direct predation (Ogutu‐Ohwayo 1993).

In the Amazon Basin, sub-basins with greater accessibility (i.e., shorter travel times from cities or closer to river ports) generally experience greater inventory effort in terms of location density and number of years inventoried, if compared to sites with less accessibility, which is one of the main limitations in fish inventories (Herrera-R et al. 2023). In the study of fish from different geomorphic habitats of the Amazonian lowlands (rivers, alluvial plains, terra firme streams, and shield streams), it is suggested to consider the temporal dynamics of habitat types and variation in hydrological seasonality (Bogotá-Gregory et al. 2023). In this sense, the basin of the Vaupés River in Colombia offers unique and incomparable study opportunities due to its remote and difficult-to-access location, in addition to its geological history, temporal and spatial variability created by rapids, make these results fill gaps of information in areas never before sampled.

The Vaupés River born in the foothills of the eastern Colombian mountain range and flows through outcrops of the Guiana Shield and sandy-soils of the Amazonian lowlands. The water chemistry of this basin is therefore a combination of sediment-rich Andean whitewaters (Unilla river sub-basin; see Fig. 1) and acidic blackwaters that drain sandy lowland rainforest soils (i.e., oxisols) of the peri-Guiana shield region (Itilla River sub-basin; see Fig. 1). The large information gaps in the area (Jézéquel et al. 2020a), the presence of endemic rheophilic species (Rineloricaria jurupari Londoño-Burbano & Urbano-Bonilla, 2018, R. daraha Rapp Py-Daniel & Fichberg, 2008, R. cachivera Urbano-Bonilla Londoño-Burbano & Carvalho, 2023), and various undescribed species (Odontocharacidium Buckup, 1993, Tetragonopterus Cuvier, 1816, Tyttocharax Fowler, 1913, Ituglanis Costa & Bockmann, 1993, Myoglanis Eigenmann, 1912, Nemuroglanis Eigenmann & Eigenmann, 1889 and Aequidens Eigenmann & Bray, 1894; Bogotá-Gregory et al. 2022a) including those in this study (i.e., Jupiaba sp., Moenkhausia sp., Phenacogaster sp., Bunocephalus sp., Hemiancistrus sp., and Archolaemus sp.) support the need to strengthen scientific expeditions and community monitoring of fish. This research should be accomplished in partnership with local indigenous communities or settlers that depend on fish for their subsistence, especially those who live in the rapids of the Vaupés River (i.e., Carurú, Matapí, Tapira Geral, La Mojarra, Macucú, Nana, Villa Fátima, and its headwaters, the Itilla and Unilla).

This study contributes new fish records for the Vaupes Arch region, a biodiverse but poorly explored region of the Colombian Amazon of high geological importance with extensive and well-preserved forested and aquatic habitats. Thes results increase the documented fish diversity of this region to 95 species, identify several putatively new species to science, and further document geographic and habitat distribution patterns. Continued systematic sampling of this region at larger spatial and temporal scales will advance progress in the knowledge of the species, populations, communities, and their habitats, especially the rapids of the Vaupés River. The taxonomic lists and high-resolution photographs made available from on public consultation platforms (CaVFfish Project - Colombia), represent important resources for monitoring, conservation, and fisheries management of the Vaupés River basin, at local, regional, national and international levels for waters shared among Brazil, Venezuela and Colombia.

We want to thank several people in indigenous communities in the region for their support: William González-Torres y Arturo Hernández (Trubón community, Cubeo ethnic group), Emilio Márquez y Anderson Márquez (Villa Fátima community, Guanano ethnic group); Adelmo Santacruz (Nana community, Guanano ethnic group); Jaider Ramírez-Samaniego (Macucú community, Desano ethnic group), Julio V. Vélez y Silvio Vélez (Matapi community, Desano ethnic group). Additionally, we thank the following people for help during the expedition Alejandro Campuzano-Zuluaga (Fundación Conservando); Luis F. Jaramillo-Hurtado (Instituto Amazónico de Investigaciones Científicas SINCHI), and Mariana A. Moscoso (Ictiología y Cultura). Thanks to Alejandro Londoño-Burbano, Angela Zanata; Bárbara Calegari; Cárlison Oliveira, Carlos DoNascimiento, Dario Faustino-Fuster, Fernando Jerep, Fernando Carvalho, Flávio Lima, Guilherme Dutra, Gustavo Ballen, Henrique Varella, Hernan López Fernandez, Henry Agudelo, José Birindelli, Manoela Marinho, Marcelo Andrade, Matthew Kolmann, Nathan Lujan, Mark Sabaj, and Priscila Madoka Ito, for help with the taxonomic identification of species. We also thank Saul Prada Pedreros for curatorial assistance in the Museo Javeriano de Historia Natural (MPUJ) fish collection, where the fishes are housed.