Neotropical Freshwater Research Articles

Expanding the knowledge of Brazilian Gastrotrich biodiversity: Freshwater Paucitubulatina (Gastrotricha: Chaetonotida) from Northeastern Brazil

ABSTRACT Knowledge of neotropical freshwater gastrotrichs, especially in Brazil, has gained momentum in the past decades, with new species being discovered yearly, accumulating in the last 30 years more than 10% of known species worldwide. Nevertheless, there is still much to accomplish in the field, with large geographical gaps to be filled, especially in continental countries such as Brazil. In the present study, we report the partial results of an expedition that, for the first time, sampled the inland waters of Alagoas, Bahía, and Pernambuco states, Northeast Region, Brazil, and found ten species belonging to five genera of Chaetonotidae. We report the first occurrence in Brazil of Chaetonotus majestuosus Grosso & Drahg, 1984, originally described from Argentina, and the second record in Brazil of Chaetonotus dadayi Schwank, 1990, originally found in Paraguay, and the first occurrence beyond ‘terra typica’ of Heterolepidodermella jureiense Kisielewski, 1991, originally discovered in Southeastern Brazil. Furthermore, we report members of species in conformity to species originally described in European countries Chaetonotus cf. persetosus Zelinka, 1889, and Chaetonotus cf. oculifer Kisielewski, 1981, although further investigations are needed to confirm the occurrence of such widespread lineages. Finally, we list three putative undescribed species related to Lepidochaetus aff. zelinkai (Grünspan, 1908), Chaetonotus aff. hoanicus Schwank, 1990 and Chaetonotus aff. acanthocephalus Valkanov, 1937. This new survey increases the list of northeast Brazilian freshwater gastrotrichs to 13 species.

Time-calibrated phylogeny of neotropical freshwater fishes.

Neotropical Freshwater Fish (NFF) fauna exhibits the greatest phenotypic disparity and species richness among all continental aquatic vertebrate faunas, with more than 6,345 species distributed across the mostly tropical regions of Central and South America. The last two decades have seen a proliferation of molecular phylogenies, often at the species level, covering almost all 875 valid NFF genera. This study presents the most comprehensive genome-wide, time-calibrated phylogenetic hypothesis of NFF species to date, based on DNA sequences generated over decades through the collaborative efforts of the multinational ichthyological research community. Our purpose is to build and curate an extensive molecular dataset allowing researchers to evaluate macroevolutionary hypotheses in the NFF while facilitating continuous refinement and expansion. Using thousands of DNA sequences from dozens of studies, we compiled a supermatrix of 51 markers for 5,984 taxa, representing 3,167 NFF species. Based on this dataset, we built the most species-rich time-calibrated phylogeny of the NFF taxa to date, summarizing the collective efforts of the ichthyological research community since the midpoint of the last century. We provide a summary review of this remarkable evolutionary history and hope this dataset provides a framework for forthcoming studies of the NFF fauna, documenting compelling, emergent patterns in the world's most diverse continental vertebrate fauna.

Forage ecology of Neotropical fish in Brazilian biomes using stable isotopes

Neotropical regions are responsible for harboring most of the global diversity of freshwater fish, providing essential ecosystem services for society. Human activities (e.g., land use changes) jeopardize aquatic ecosystems as well as species, communities, etc., impairing ecosystem services. We investigate the impact of human disturbance on the foraging ecology of Neotropical freshwater fishes across five Brazilian biomes by stable isotope analysis. We analyzed carbon (δ13C) and nitrogen (δ15N) isotopic compositions of Neotropical fishes, sourced from the SIA-BRA dataset. Fishes were categorized into herbivores, omnivores, and carnivores. We tested the correlation between human disturbances, indicated by the human disturbance index (hdi), and changes in fish diets. We expected that the assimilation of C4‑carbon from exotic forage would increase with higher disturbance levels, while δ15N levels would similarly rise due to nitrogen input from anthropogenic sources. We found increases in fish δ13C with human disturbance increases, suggesting greater assimilation of C4 carbon in places where native vegetation was replaced by C4 sources, confirmed by isotopic mixing models. In contrast, δ15N values did not show a significant relationship with human disturbance, probably due to the complex interactions and multiple sources of nitrogen in disturbed environments. Our finds suggest that stable isotope analysis provides a powerful tool for monitoring the effects of landscape changes on aquatic food webs. Particularly, the δ13C values of detritivorous fish that feed on C4 plant detritus could serve as bioindicators of environmental degradation. However, a specific isotopic characterization of each site would be valuable for more accurate niche information.

Recent dispersion routes between freshwater ecoregions evidence headwater captures in southern Brazil: a case study using cryptic species of the neotropical freshwater fish genus Cambeva (Siluriformes: Trichomycteridae)

Recent dispersion routes between freshwater ecoregions evidence headwater captures in southern Brazil: a case study using cryptic species of the neotropical freshwater fish genus Cambeva (Siluriformes: Trichomycteridae)

External morphology and growth patterns of larvae and juveniles of Bryconops gracilis (Characiformes, Iguanodectidae) from Amazon basin

During early development, fishes undergo significant changes that influence external morphology and the functioning of internal organs and systems. This often results in gradual variation of the morphological traits of individuals across developmental stages. The investigation of larval and juvenile fish development and growth patterns has pertinent implications for the systematic and ecological elucidation of species. Bryconops gracilis is a medium-sized fish, omnivorous that inhabits lotic and lentic environments with acidic and transparent waters in the Amazon basin. In this study, the early development of B. gracilis is described, until recently a practically unknown species. In terms of development, we used morphological, meristic, and morphometric data to characterize the larvae and juveniles. The individuals were collected in the Curuá-Una River, Amazon basin, Brazil. Fifty-four specimens were examined. Samples include individuals with 3.39 to 21.79mm SL. Yolk-sac larvae have two attachment organs on the dorsal surface of head and body. The larvae of B. gracilis are considered altricial, with a fusiform body, and the intestine reaches the median region of the body. Initially, the mouth is subterminal and becomes isognathic from the postflexion stage on. During the postflexion stage, the most relevant morphological changes occur (e.g., presence of all fins, mouth position similar to adults, increased body pigmentation), making individuals more specialized to explore new habitats and diets and maximize their chances of survival. Furthermore, vertebrae and myomeres are compared and assist with differentiating some Bryconops species at early life stages that occur in sympatry in the Amazon basin. Our results contribute to knowledge about the external morphology of neotropical freshwater fishes, enabling the identification of larvae and juveniles through traditional taxonomy and broadening the perspective on the ontogenetic study of the adipose fin in Characoidei.

Influence of isolation on the resilience of tank bromeliad ecosystems to drought in a Neotropical rainforest

Little is known of how Neotropical freshwater ecosystems will respond to future climate scenarios. In Neotropical rainforests, a substantial fraction of the freshwater available to the aquatic fauna is found within phytotelmata, plant-held waters that form aquatic islands in a terrestrial matrix. We hypothesized that phytotelmata in close proximity have higher resilience capacity to severe drought than the isolated ones, under the assumption that immigration from nearby sources promotes faster recovery. We used rainshelters to emulate an extreme drought (67 days without rainfall) in tank-forming bromeliads arranged in patches of 1, 3 or 6 plants in a primary forest of French Guiana. Habitat size was a stronger determinant of invertebrate species richness and biomass per bromeliad than patch size. Larger bromeliad patches attenuated the adverse effect of drought on the biomass of predators, probably because short-range migration within dense patches allowed individuals to find moist refuges. However, the recovery of aquatic communities and ecosystem functions was mostly supported by in situ resistance, and a rescue effect of immigration was weak. Whilst environmental management plans tend to focus on dense networks of connected water bodies, our study shows that efforts should not omit the isolated ones.

Effect of fire and environmental temperature on the reproductive recruitment of Neotropical freshwater turtles

Effect of fire and environmental temperature on the reproductive recruitment of Neotropical freshwater turtles

The neurocranium of Potamotrygonidae: morphology and phylogenetic significance

Abstract The family Potamotrygonidae is part of the Neotropical ichthyofauna and has the largest diversity of freshwater elasmobranchs in the world. The neurocranium in Potamotrygonidae is an elongated and dorsoventrally flattened structure that articulates anterolaterally with the anterior portion of the propterygium, posteriorly with the sinarcual, and posterolaterally with the hyomandibula. This anatomical structure is comparatively described in Potamotrygonidae in an effort to reveal new phylogenetically relevant characters. Additionally, a new genus-level phylogeny of the family is proposed herein based on 60 novel morphological characters. The subfamily Potamotrygoninae, whose monophyly is well sustained by previous studies, is further supported herein by a variable number of cranial synapomorphies (up to 17), depending on the optimization adopted. Furthermore, we also recovered Potamotrygon and Plesiotrygon as consecutive sister-groups to a clade including Heliotrygon and Paratrygon. The neurocranium of potamotrygonids and its anatomical variation is also discussed in the context of previous morphological and molecular phylogenies of Neotropical freshwater stingrays.

Remodeling of Uterine Tissues During Gestation of Potamotrygon wallacei (Elasmobranchii), a Neotropical Freshwater Stingray Endemic to the Negro River, Central Amazonia.

Neotropical freshwater stingrays of the subfamily Potamotrygoninae exhibit aplacental viviparity with uterine trophonemata. In this reproductive mode, females nourish and provide oxygenation to the embryo via the mucosa of the uterine wall. The aim of this study was to describe and histologically quantify the tissue components of the gravid uterus in an Amazonian freshwater stingray. Adult females of Potamotrygon wallacei were studied in different reproductive periods: resting stage, pregnant, and postpartum. During reproductive rest, the left ovary has numerous follicles compared to the right side. Therefore, uterine fertility is usually higher on the left side. The presence of an embryo in the right uterus suggests that the right ovary is also functional, although this only occurs in larger females. In females at reproductive rest, the wall of the uterus is formed by a mucosal layer (without the trophonemata) that contributes 16.7% to the thickness, while the myometrium accounts for 83.3% of the thickness. The mass-specific volume of the mucosal layer, inner circular, and outer longitudinal smooth muscle sheets tend to increase in the gravid uterus, indicating hypertrophy and hyperplasia of these components. During pregnancy, the trophonemata undergo marked tissue remodeling. Epithelial cells are organized into glandular acini and have apical secretory vesicles; furthermore, peripheral blood vessels proliferate and become dilated. These characteristics demonstrate that the gravid uterus of P. wallacei presents intense uterolactation activity and provides oxygenation to the fetus. Tissue remodeling occurs only in the uterus with the presence of an embryo. During postpartum, females have low body condition factor indicating a high reproductive cost. This study contributes to the knowledge of the reproductive biology of this species and will help us understand the impacts of climate change on the breeding areas of potamotrygonids.

Morphology of the Digestive Tube of the Amazonian Freshwater Stingray Potamotrygon wallacei (Elasmobranchii: Potamotrygonidae): A Stereological Approach.

This work aimed to describe and quantify the tissue components of the digestive tube of the neotropical freshwater stingray, Potamotrygon wallacei. For this, conventional histology and stereological methods were used to estimate tissue volume. The volumes of the four fundamental layers and the tissue components in the stomach (cardiac and pyloric) and spiral intestine were also estimated. In the cardiac stomach, the mucosa layer occupies 44.7% of the total volume of the organ wall. The gastric glands are the main components, and these structures alone represent 49.7% of this layer. This large number of gastric glands suggests a high potential for processing food items with a high protein content. The stereological methods were sensitive enough to show a reduction in the volume of the gastric glands from the cardiac region toward the pyloric region. Gastric glands are absent in the pyloric region of the stomach. However, the muscularis becomes thicker towards the pyloric region. The increase in smooth muscle thickness is due to the thickening of the inner muscular layer. This suggests that the role of the pyloric stomach may be related to the mixing of the chyme and assisting its passage to the spiral intestine. In the spiral intestine, data on the volume of the mucosa layer (and epithelial lining) suggest that the spiral valve has a large absorptive area. In several respects, the morphology of the digestive tube of P. wallacei is similar to that of other batoids. However, its slight morphological variations may be related to the habitat specificity of this species.

Diversity and ecological relationships of Cestoda and Monogenoidea parasites of freshwater stingrays (Myliobatiformes, Potamotrygonidae), in the upper Paraná River, Brazil

The Neotropical freshwater stingrays of Potamotrygon genus present a unique and complex natural history and biogeographical pattern that can be traced to a marine origin and the colonization of the continental environment during the Miocene. During the evolution of potamotrygonids, several species of the parasitic fauna coevolved and co-opted concomitantly to their hosts during the colonization of the new environments. One striking example can be observed during the colonization of the upper Paraná River region. However, few studies explored the ecological and taxonomic aspects of potamotrygonid parasites. In this work, we investigate aspects of the ecology and taxonomy of the species of Monogenea and Cestoda that are parasites the species of freshwater stingrays of the genus Potamotrygon in the upper Paraná River. Our results indicate that at least six species of parasites are present in potamotrygonids in the region. Two of the observed parasites are putative new species and three of the parasitic species were identified for the first time in the region, hence expanding their geographic distributions. We quantified ecological aspects at different levels of communities for the collected parasite species. We compared the diversity in different locations and hosts and performed an exploratory analysis to investigate the differences in parasite abundance. Additionally, an identification key for the Monogenea and Cestoda species of the sampled region is provided.

The mechanosensory world in aquatic snakes: corporal scale sensilla in three species of Neotropical freshwater dipsadine

Snakes have diverse and unique sensory systems that make them extremely efficient at moving through the environment while detecting prey and predators and performing courtship behaviors. In recent years, the number of studies on the mechanoreception of aquatic snakes has increased, principally focusing on the ecological and sexual roles of cephalic mechanoreceptors or sensilla. However, few studies have focused on the presence and role of corporal mechanoreceptors sensilla in freshwater snakes. This study describes the morphology of dome-shaped corporal scale sensilla for the first time in three species of aquatic Neotropical snakes (Helicops angulatus, Helicops danieli, and Helicops pastazae), using histological sections and Scanning Electron Microscopy (SEM). Histological sections revealed that the corporal sensilla resemble the previously described cephalic sensilla with a thinner beta keratin layer above the sensillum, and a group of central cells. Further, SEM images show dome-shaped protuberant organs with concentric rings. To infer possible ecological and sexual roles in corporal sensilla, we employed mixed ANOVA permutation tests to assess for differences in the number and area of sensilla between the dorsal and lateral position of the scales, and the anterior and posterior corporal region, as well as among species and sexes. Our results show that individuals across all species consistently exhibited a higher number of mechanoreceptors sensilla in the anterior and lateral region when compared to the posterior or midbody dorsal region. We qualitatively identified that scale sensilla are usually restricted to the keeled portion of the scale in the dorsal region, but are spread out throughout the scale in the lateral region. We also found differences in the average sensillum area between species, with H. angulatus exhibiting larger sensilla than H. danieli. Our results showed no evidence of sexual dimorphism in the number or area of corporal sensilla. These findings are the first to report corporal dome shaped mechanoreceptors in freshwater snakes and contribute to the understanding of mechanosensory systems in these organisms by elucidating the morphology, quantity, distribution and possible function of these corporal scale sensilla.

Chromosomal analysis of two Acanthodoras species (Doradidae, Siluriformes): Insights into the oldest thorny catfish clade and its karyotype evolution.

The Doradidae fishes constitute one of the most diverse groups of Neotropical freshwater environments. Acanthodoradinae is the oldest lineage and the sister group to all other thorny catfishes, and it includes only the genus Acanthodoras. The diversity of Acanthodoras remains underestimated, and the use of complementary approaches, including genetic studies, is an important step to better characterize this diversity and the relationships among the species within the genus. Therefore, we conducted a comprehensive analysis using conventional cytogenetic techniques and physical mapping of three multigene families (18S and 5S ribosomal DNA [rDNA], U2 small nuclear DNA [snDNA]) and four microsatellite motifs, namely (AC)n, (AT)n, (GA)n, and (GATA)n, in two sympatric species from the Negro River: Acanthodoras cataphractus and Acanthodoras cf. polygrammus. We found significant differences in constitutive heterochromatin (CH) content, distribution of the microsatellite (AT)n, and the number of 5S rDNA and U2 snDNA sites. These differences may result from chromosome rearrangements and repetitive DNA dispersal mechanisms. Furthermore, the characterization of the diploid number (2n) of these Acanthodoras species enables us to propose 2n = 58 chromosomes as the plesiomorphic 2n state in Doradidae based on ancestral state reconstruction. Acanthodoradinae is the oldest lineage of the thorny catfishes, and knowledge about its cytogenetic patterns is crucial for disentangling the karyotype evolution of the whole group. Thus, this study contributes to the understanding of the mechanisms behind chromosome diversification of Doradidae and highlights the importance of Acanthodoradinae in the evolutionary history of thorny catfishes.

Underestimated diversity in Characidium (Characiformes: Crenuchidae) from Neotropical rivers revealed by an integrative approach

Characidium represents the most widely distributed and species-rich fish genus within the family Crenuchidae in the Neotropical region, with numerous species described over the last decade. Despite this taxonomic progress, the understanding of species boundaries and population variation within the genus remains limited. In response, an integrative study was undertaken, utilizing both morphological and molecular data from neotropical freshwater ecoregions with rivers that drain the Brazilian northeastern. The primary objective of this investigation was to elucidate taxonomic delimitations and, where relevant, propose new species hypotheses. Our results propose the existence of 15 operational taxonomic units (OTUs) as species hypotheses. Among these, 10 were identified as valid species, four represented morphotypes that hold the potential of constituting new species, and one OTU was determined as a new species, corroborated by all proposed delimitation methods. Our results demonstrated discrepancies between morphological and molecular data, highlighting the challenges in defining taxonomic boundaries within Characidium. Moreover, our findings provided insights into the intricate diversification history of Characidium species, applied to the species that occur in northeastern Brazilian drainages. We proposed that historical events, such as river connections and barriers, have played a significant role in shaping the current distribution patterns of the genus.

Chromosomal mapping of repetitive DNA and retroelement sequences and its implications for the chromosomal evolution process in Ctenoluciidae (Characiformes)

Ctenoluciidae is a Neotropical freshwater fish family composed of two genera, Ctenolucius (C. beani and C. hujeta) and Boulengerella (B. cuvieri, B. lateristriga, B. lucius, B. maculata, and B. xyrekes), which present diploid number conservation of 36 chromosomes and a strong association of telomeric sequences with ribosomal DNAs. In the present study, we performed chromosomal mapping of microsatellites and transposable elements (TEs) in Boulengerella species and Ctenolucius hujeta. We aim to understand how those sequences are distributed in these organisms’ genomes and their influence on the chromosomal evolution of the group. Our results indicate that repetitive sequences may had an active role in the karyotypic diversification of this family, especially in the formation of chromosomal hotspots that are traceable in the diversification processes of Ctenoluciidae karyotypes. We demonstrate that (GATA)n sequences also accumulate in the secondary constriction formed by the 18 S rDNA site, which shows consistent size heteromorphism between males and females in all Boulengerella species, suggesting an initial process of sex chromosome differentiation.

Integrative approach revealing a species complex in the Neotropical freshwater crab Dilocarcinus septemdentatus (Herbst, 1783) (Decapoda: Trichodactylidae) with a description of a new species

The taxonomic status of the freshwater crab Dilocarcinus septemdentatus (Herbst, 1783) is still not well established. Currently, the main issue involves synonymization with D. spinifer H. Milne Edwards, 1853, based on a variation of the angulation of the gonopod apex. These species are distributed along rivers and lakes in northern South America, with disjunct occurrences in central-west Brazil and Argentina. Due to these inconsistencies, an integrative approach was performed to elucidate these questions, with morphological (including NanoCT-Scan) and molecular analysis (Maximum Likelihood Trees, Bayesian Inference, Genetics Distance Matrix, and Haplotype Network), based on mitochondrial markers COI and 16S rRNA. Both analysis revealed and supported the existence of a species complex under the name of D. septemdentatus. Based on the results obtained, we propose the revalidation of D. spinifer, the description of a new species, and the redescription of D. septemdentatus s. str., with a neotype designation for this species. The hypothesis that this species complex originated in the Pebas System, an extensive mega wetland system that existed along the lowlands of Western Amazonia from late Oligocene to late Miocene (c. 23–11 mya) is discussed.

Phenotypic Convergence Is Stronger and More Frequent in Herbivorous Fishes.

Constraints on phenotypic evolution can lead to patterns of convergent evolution, by limiting the "pool" of potential phenotypes in the face of endogenous (functional, developmental) or exogenous (competition, predation) selective pressures. Evaluation of convergence depends on integrating ecological and morphological data within a robust, comparative phylogenetic context. The staggering diversity of teleost fishes offers a multitude of lineages adapted for similar ecological roles and, therefore, offers numerous replicated evolutionary experiments for exploring phenotypic convergence. However, our understanding of fish feeding systems has been primarily shaped by marine species, with the monolithic exception of freshwater cichlids. Here we use piranhas and pacus (Serrasalmidae) to explore the evolution of different feeding ecologies and their morphological proxies in Neotropical freshwater environments. Specifically, we explore whether convergence is more widespread among plant-eating fishes, arising from strong constraints on phenotypic evolution in herbivores. Using osteological micro-computed tomographic imaging (μCT), we describe the major axes of morphological variation in pacus and piranhas, regarding their diet and feeding behaviors. Next, we evaluated whether herbivorous niches are less labile than other dietary guilds and whether herbivorous species' phenotypes evolve at a slower evolutionary rate than other taxa. We then assess how convergent herbivorous taxa are, using three different suites of morphological characters (dental, jaw, and abdominal morphometrics). Ecologically, herbivory is not a dead end, exhibiting similar observed transition rates as those between carnivores and omnivores. However, we documented widespread convergence in herbivores and that herbivores have slower rates of phenotypic evolution than carnivores. Most instances of convergence are found in herbivorous taxa, specifically in frugivores and folivores. Moreover, instances of "complete" convergence, indicated by positive convergence metrics observed in more than one morphometric dataset, were only found in herbivores. Herbivores do appear to evolve under constrained circumstances, but this has not limited their ecological ability.

Assessing the spatial knowledge gaps of Odonata diversity and conservation in the South American Pampa

Abstract Anthropogenic activities highly threaten neotropical freshwater habitats. Aquatic insects are sensitive to environmental alterations and thus considered under great risk due to such pressures. However, large‐scale gaps regarding the knowledge of the distribution of aquatic insect species remain in the Neotropics, particularly in the South American temperate grasslands (Pampas), hindering the knowledge of hotspots of aquatic insect diversity and the prioritization of conservation areas destined to protect their populations. Here, we review the current knowledge regarding the geographical distribution of Odonata species and use ecological niche models to estimate the areas with the highest potential richness of Odonata species in the Pampas. We also calculate a sampling effort index and interpolate it with maps of protected areas to identify the spatial knowledge gaps regarding their conservation in the region Our compilation of Odonata species records retrieved 237 species for the Pampa. However, Odonata species were recorded in less than 2% of the Pampa. Our findings indicated a higher potential diversity of Odonata in northeastern Argentina, southern Uruguay and southern Brazil. Interpolations of sampling effort index and protected areas showed that 95% of the area potentially rich in Odonata species fall outside protected areas. Our study highlights the shortfall regarding the knowledge of the distribution of Odonata diversity in non‐forest landscapes of the Neotropical region. It also shows that protected areas of the Pampa cover a minor area of the Odonata species range in the region.

BETWEEN BUCCAL PUMPING AND BITING - EVIDENCE OF INTRAUTERINE MOUTH MOVEMENTS AND REPRODUCTIVE ASPECTS OF NEOTROPICAL FRESHWATER STINGRAYS (Elasmobranchii: Potamotrygoninae)

Preliminary findings regarding the reproduction of three neotropical freshwater stingray species, Potamotrygon henlei, P. motoro, and P. orbignyi, are presented herein. These species are characterized by the presence of a singular functional left ovary and two operational uteri. Two distinct fertility models have been identified: fecundity dependent, and fecundity independent of maternal size. Furthermore, this study briefly outlines the process of capture-induced parturition and its implications for the fate of the litter. Additionally, it sheds light on novel embryonic behavioral patterns, particularly highlighting the active swimming exhibited by embryos within the uterine environment, notably during the latter stages of development. Consequently, it is suggested that these movements, coupled with oral activities and active biting, facilitate branchial ventilation and potentially intrauterine foraging - a phenomenon previously documented only in sharks belonging to the order Lamniformes. Keywords: Abortion, Histotroph, Capture stress, Embryonic nutrition.

Guiding the path of larvae: The potential of light traps in Neotropical freshwater fish research

Light traps are devices utilized in biomonitoring studies across various aquatic environments. Although light traps are used globally, few studies report their efficacy in capturing fish larvae in the Neotropics. To address this gap, this study aimed to assess the efficacy of light traps in capturing larvae of six fish species commonly found in Neotropical rivers. Additionally, we aimed to evaluate the effect of light color on larval capture. To accomplish this, we selected larvae from six species: Cyprinus carpio, Ctenopharingodon idella, Piaractus mesopotamicus, Pimelodus maculatus, Prochilodus lineatus, and Rhamdia quelen. Each experiment lasted seven days, and six types of traps were tested, including those without light (control) and those with light (green, red, yellow, white, and blue), and installed in triplicate. A total of 18 traps were randomly positioned in earthen ponds containing the six species of interest. Each species was assessed separately in six experiments. Larvae were counted, measured, and identified daily according to their developmental stage. The light traps collected 30,498 larvae, whereas the control traps only collected 39 larvae by the end of the experiment. Larvae from species of the Cypriniformes order were the most captured, while those from the Siluriformes order were least captured. The light traps exhibited selectivity in capturing larvae at different developmental stages, which varied according to species. Traps installed with green lights captured a greater number of larvae and were more efficient at capturing larvae from a wider variety of species. In contrast, traps installed with red light led to the capture of fewer larvae. Therefore, by their ability to attract a greater number of larvae, compared to control, and selectively capture larvae at different developmental stages at variable rates, depending on light source, light traps can be a valuable tool in biomonitoring and managing fish larvae in Neotropical environments.