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The reproductive behaviour of the Andean catfish Astroblepus ubidiai was observed directly and with an underwater camera in a spring located next to Lago San Pablo in the province of Imbabura, Ecuador, in late 2015 and early 2016. Five mating attempts were observed, four of which were video-taped, and two of which resulted in complete copulation. During copulation, the male grabs the female from the top of the head with its buccal disc and pelvic fins and, from this position, bends its body forming a "C" to reach the genital pore of the female and introduce its copulatory organ. Once copulation is complete, the female swims away rapidly. Details of the copulation are described here through illustrations.

The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's most diverse regions for freshwater fishes. Our NEOTROPICAL FRESHWATER FISHES data set is the first to produce a large-scale Neotropical freshwater fish inventory, covering the entire Neotropical region from Mexico and the Caribbean in the north to the southern limits in Argentina, Paraguay, Chile, and Uruguay. We compiled 185,787 distribution records, with unique georeferenced coordinates, for the 4225 species, represented by occurrence and abundance data. The number of species for the most numerous orders are as follows: Characiformes (1289), Siluriformes (1384), Cichliformes (354), Cyprinodontiformes (245), and Gymnotiformes (135). The most recorded species was the characid Astyanax fasciatus (4696 records). We registered 116,802 distribution records for native species, compared to 1802 distribution records for nonnative species. The main aim of the NEOTROPICAL FRESHWATER FISHES data set was to make these occurrence and abundance data accessible for international researchers to develop ecological and macroecological studies, from local to regional scales, with focal fish species, families, or orders. We anticipate that the NEOTROPICAL FRESHWATER FISHES data set will be valuable for studies on a wide range of ecological processes, such as trophic cascades, fishery pressure, the effects of habitat loss and fragmentation, and the impacts of species invasion and climate change. There are no copyright restrictions on the data, and please cite this data paper when using the data in publications.

Hemigrammus unilineatus (Gill, 1858) (Characidae) is rediscovered in Yasuní National Park, eastern Ecuador, where it has not been reported since 1987. We present a detailed taxonomic description, including measurements and photographs, as well as a distribution map of this species in Ecuador. Based on our new evidence, we confirm the presence of H. unilineatus in the Ecuadorian Amazon.

Los estudios sobre hábitos alimentarios de comunidades acuáticas ayudan a entender cómo estas interactúan, y considerando que los peces de páramo han sido muy poco investigados, se analizó la dieta y se contribuyó al entendimiento de la ecología trófica de Grundulus quitoensis, especie endémica de los andes del Ecuador. Se estudió el contenido estomacal de 26 ejemplares de la laguna El Voladero. Se identificaron doce categorías de presa, de las cuales, el género Bosmina (Crustacea: Cladocera) (Ni = 2410; Fo = 22) y entidades de la familia Chironomidae (Insecta: Diptera) (Ni = 466; Fo = 46) presentan la mayor abundancia. El factor de condición alométrico (K) obtuvo valores entre 0,11–0,77, significando que los ejemplares se encontraban en condiciones de poca alimentación. Aunque la dieta de esta especie es amplia, consume en gran cantidad insectos y microcrustáceos. Es necesario preservar la laguna El Voladero para conservar su biodiversidad única.

A review of the species of the genus Mylossoma Eigenmann & Kennedy, 1903 found in the Ecuadorian Cis-Andeanregion was conducted. Two species were recognized: M. albiscopum (Cope, 1872) from the Putumayo, Napo, andTigre river basins and M. aureum (Agassiz, 1829) from the Napo river basin. A map of geographical distribution andradiographs for both species are provided. Historical records of M. duriventre (Cuvier, 1818) were not confirmed inthis geographical distribution.

Freshwater fish communities in Ecuador exhibit some of the highest levels of diversity and endemism in the Neotropics. Unfortunately, aquatic ecosystems in the country are under serious threat and conditions are deteriorating. In 2018–19, the government of Ecuador sponsored a series of workshops to examine the conservation status of Ecuador''s freshwater fishes. Concerns were identified for 35 species, most of which are native to the Amazon region, and overfishing of Amazonian pimelodid catfishes emerged as a major issue. However, much of the information needed to make decisions across fish groups and regions was not available, hindering the process and highlighting the need for a review of the conservation threats to Ecuador''s freshwater fishes. Here, we review how the physical alteration of rivers, deforestation, wetland and floodplain degradation, agricultural and urban water pollution, mining, oil extraction, dams, overfishing, introduced species and climate change are affecting freshwater fishes in Ecuador. Although many of these factors affect fishes throughout the Neotropics, the lack of data on Ecuadorian fish communities is staggering and highlights the urgent need for more research. We also make recommendations, including the need for proper enforcement of existing environmental laws, restoration of degraded aquatic ecosystems, establishment of a national monitoring system for freshwater ecosystems, investment in research to fill gaps in knowledge, and encouragement of public engagement in citizen science and conservation efforts. Freshwater fishes are an important component of the cultural and biological legacy of the Ecuadorian people. Conserving them for future generations is critical. © 2021 The Authors. Journal of Fish Biology published by John Wiley & Sons Ltd on behalf of Fisheries Society of the British Isles.

A new species of catfish is described from the Esmeraldas River Basin, Pacific slope, northern Ecuador. Tentatively included in Microglanis, represents the second species of the genus inhabiting the Trans-Andean region. The new species is distinguished from known congeners by a unique combination of external characteristics: head and body color pattern, uniform, pale brown, yellowish or grayish, without any kind of blotches, bands or dots, only a lunate transverse band, dark or black, at caudal-fin origin; adipose-fin origin and forward without lighter or luminous areas. Compared with M. variegatus, the new species has morphometric differences, such as the distances between dorsal and pelvic fins, and between posterior nostrils. Some osteological characteristics are compared with those observed in species of Pseudopimelodidae inhabiting the Pacific versant of Colombia and Ecuador and with some other species of Microglanis. RESUMEN Se describe una nueva especie de bagre para la cuenca del río Esmeraldas, vertiente del Pacífico, en el norte de Ecuador. Incluida tentativamente en Microglanis, representa la segunda especie del género que habita en la región transandina. La nueva especie se distingue de los congéneres conocidos por una combinación única de características externas, que incluyen: patrón de color de la cabeza y el cuerpo, uniforme, marrón pálido, amarillento o grisáceo, sin ningún tipo de manchas, bandas o puntos, excepto una banda transversal alunada, oscura o negra, en el origen de la aleta caudal; origen de la aleta adiposa y región anterior sin áreas más claras o luminosas. En comparación con M. variegatus, la nueva especie tiene diferencias morfométricas, como las distancias entre las aletas dorsal y pélvica, y entre las narinas posteriores. Algunas características osteológicas se comparan con las observadas en especies de Pseudopimelodidae que habitan en la vertiente del Pacífico de Colombia y Ecuador, y en algunas otras especies de Microglanis.

The Amazon Basin is an unquestionable biodiversity hotspot, containing the highest freshwater biodiversity on earth and facing off a recent increase in anthropogenic threats. The current knowledge on the spatial distribution of the freshwater fish species is greatly deficient in this basin, preventing a comprehensive understanding of this hyper-diverse ecosystem as a whole. Filling this gap was the priority of a transnational collaborative project, i.e. the AmazonFish project - https://www.amazon-fish.com/. Relying on the outputs of this project, we provide the most complete fish species distribution records covering the whole Amazon drainage. The database, including 2,406 validated freshwater native fish species, 232,936 georeferenced records, results from an extensive survey of species distribution including 590 different sources (e.g. published articles, grey literature, online biodiversity databases and scientific collections from museums and universities worldwide) and field expeditions conducted during the project. This database, delivered at both georeferenced localities (21,500 localities) and sub-drainages grains (144 units), represents a highly valuable source of information for further studies on freshwater fish biodiversity, biogeography and conservation., Measurement(s)Diversity • Fish • spatial patternTechnology Type(s)digital curationFactor Type(s)geographic locationSample Characteristic - OrganismfishSample Characteristic - Environmentdrainage basinSample Characteristic - LocationAmazon Basin Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.11920800

An annotated list of the freshwater fishes of the Limoncocha Lagoon, in the Limoncocha Biological Reserve in thenorthern Amazon region of Ecuador is presented. Fishes were captured between March and July of 2012, and wecombined these results with previous studies to provide a comprehensive list of fishes in the Limoncocha BiologicalReserve. Thirty-three species belonging to 14 families distributed in 7 orders were collected. The most representativeorders in number of species and specimens were Characiformes, Siluriformes, and Perciformes, respectively, beingCharaciformes as the most important in terms of richness and abundance of species. Characidae (Characiformes)exhibited the greatest abundance and broadest distribution in our samples. A short morphological description andmorphometric measurements of each species are also presented.

La fecundidad relativa en peces es la estimación de la cantidad de ovocitos de una hembra por desove. Este aspecto se investigó en especímenes topotipos de Grundulus quitoensis de la laguna altoandina El Voladero, Ecuador. Se identificó el estadio de madurez gonadal (maduro e inmaduro) a través de la observación directa, se calculó la fecundidad relativa al peso (FRP) y a la longitud total (LT). Las hembras estudiadas tuvieron en promedio una LT de 63,9 mm. El rango de ovocitos varió entre 75 y 716 por hembra y en total se contaron 5691 ovocitos para 16 hembras. El PT varió entre 0,5 g y 4,7 g; mientras que la LT varió entre 36,7 mm a 63,9 mm. La fecundidad relativa se observó comprendida entre 1,6 y 14,3 ovocitos por mm de LT del animal (X ̅= 6,9 ± 3,6 mm-1) y entre 47,2 y 319,1 ovocitos por g de peso total (X ̅= 148,9 ± 74,9 g-1). Es importante conocer el ciclo de vida e historia natural de una especie, porque contribuyen al conocimiento ecológico de los peces que habitan las lagunas altoandinas, como es el caso del estudio aquí desarrollado en G. quitoensis.

The leucism is an aberration in pigmentation, resulting from a genetic abnormality and occurs in all vertebrate groups in which the fish are included. In Ecuador it has not reported such anomalies in fish. Is presented for the first time a case of partial leucism in an individual of Andean Catfish (Astroblepidae), observed in a spring located near the Lake San Pablo Canton Otavalo, Imbabura Province, Ecuador.

We report collections of several specimens of Sicydium in 2013 and 2014 from the Jubones and Santa Rosa Rivers in southwestern Ecuador. These collections substantially expand the known range of the genus southward. The specimens are tentatively identified as Sicydium cf. rosenbergii based on their morphology. Small differences in morphology among specimens from the two rivers are noted, as are discrepancies with the type description. A museum database search uncovered two additional records of the genus south of their previously recognized range including one record from northwestern Peru.

Neotropical mountain streams are important contributors of biological diversity. Two species of the characid genus Rhoadsia differing for an ecologically important morphological trait, body depth, have been described from mountain streams of the western slopes of the Andes in Ecuador. Rhoadsia altipinna is a deeper-bodied species reported from low elevations in southwestern Ecuador and northern Peru, and Rhoadsia minor is a more streamlined species that was described from high elevations (>1200 m) in the Esmeraldas drainage in northwestern Ecuador. Little is known about these species and their validity as distinct species has been questioned. In this study, we examine how their body shape varies along replicated elevational gradients in different drainages of western Ecuador using geometric morphometrics and the fineness ratio. We also use sequences of the mitochondrial cytochrome oxidase c I gene and the second intron of the S7 nuclear gene to examine whether genetic data are consistent with the existence of two species. We found that body depth varies continuously among populations within drainages as a function of elevation, and that body shape overlaps among drainages, such that low elevation populations of R. minor in the Esmeraldas drainage have similar body depths to higher elevation R. altipinna in southern drainages. Although a common general trend of declining body depth with elevation is clear, the pattern and magnitude of body shape divergence differed among drainages. Sequencing of mitochondrial and nuclear genes failed to meet strict criteria for the recognition of two species (e.g., reciprocal monophyly and deep genetic structure). However, there was a large component of genetic variation for the COI gene that segregated among drainages, indicating significant genetic divergence associated with geographic isolation. Continued research on Rhoadsia in western Ecuador may yield significant insight into adaptation and speciation in Neotropical mountain streams.

The leucism is an aberration in pigmentation, resulting from a genetic abnormality and occurs in all vertebrate groups in which the fish are included. In Ecuador it has not reported such anomalies in fish. Is presented for the first time a case of partial leucism in an individual of Andean Catfish (Astroblepidae), observed in a spring located near the Lake San Pablo Canton Otavalo, Imbabura Province, Ecuador.

Los peces Brycon dentex y Hamuelopsis elongatus fueron colectados por primera vez en la zona ictiohidrográfica de Santiago-Cayapas, en los ríos Mira y Camumbi, cuenca fluvial del río Mira, parroquia Tobar Donoso, provincia del Carchi, Ecuador. Los registros previos de estas especies venían de las zonas ictiohidrográficas Esmeraldas e Intermareal, respectivamente.