Fish Species Diversity Research Articles

Fish Biodiversity at Kawadighi Haor of Northeastern Bangladesh: Addressing Fish Diversity, Production and Conservation Status

This research was conducted to explore the status of fish species diversity and production in the Kawadighi Haor of northeastern Bangladesh. Data were collected biweekly through direct catch assessment surveys, focus group discussions, and personal interviews using a questionnaire. A total of 87 fish and prawn species belonging 14 orders and 30 families were identified in the Haor, where 18% species were abundantly available, 20% were commonly available, 42% were moderately available and 20% were rarely available. Among the recorded species, Cypriniformes, having 34 species, had the most species, followed by Siluriformes (20), Anabantiformes (11), Ovalentaria (4), Synbranchiformes (4), Clupeiformes (3), Decapoda (3), Osteoglossiformes (2), Anguilliformes (1), Beloniformes (1), Cyprinodontiformes (1), Gobiiformes (1), Mugiliformes (1), and Tetraodontiformes (1). The values of Shannon-Weaver diversity (H), Margalef’s richness (d), and Pielou’s evenness (J) indices were 2.98, 7.72 and 0.67 in Hawagulaia, 2.97, 7.52 and 0.67 in Patasingra and 2.61, 7.30 and 0.59 in Salkatua beel, respectively. The haor's average yearly fish production was 704.09 kg/ha. Small indigenous species (SIS) of fish dominated the haor's total production, accounting for 51.8 to 70.57 percent of the total contribution. The highest portion of fish produced in the non-stocked beel was SIS of fish but per hectare SIS of fish production of non-stocked beel was lower than the fingerling stocked beels. Aquaculture might have a good effect on fish production and biodiversity. The findings showed that Kawadighi Haor is a very productive and biodiversity-rich inland open waterbody that may function as a mother fishery. For the protection of current fisheries resources, multiple approaches including public awareness campaigns might be beneficial. 

Fish Image Classification Using Adaptive Learning Rate In Transfer Learning Method

The existence of fish species diversity in coastal ecosystems which include mangrove forests, seagrass beds and coral reefs is one of the benchmarks in determining health in coastal ecosystems. It is certain that we must maintain, preserve and care for so that conservation efforts need to be carried out in water areas. Many experts at the Indonesian Fisheries and Marine Research and Development Agency often classify fish images manually, of course it will take a long time, therefore with today's developments they can use the latest technology. One of the reliable techniques in terms of image classification is Convolutional Neural Network (CNN). As time goes by, of course, many people want fast learning and solving new problems faster and better, so transfer learning appears, which adopts part of CNN, the name is modified convolution layer. Observing the needs of experts in the field of marine conservation, the researchers decided to solve this problem by using transfer learning modifications. The transfer learning used is an architectural model from the pre-trained Mobilenet V2, which is known for its light computing process and can be applied to our gadgets and other embedded tools. The research image data used is 49.281 data of various sizes and there are 18 types of fish, in the pre-processing data there is a resize of the image to a size of 224x224 pixels. testing with the modified transfer learning architectural model obtained an accuracy score of 99.54%, this model is quite reliable in classifying fish images.

BIOLOGICAL CHARACTERISTICS OF THE FISH FAUNA IN THE SEVERNAYA DVINA ESTUARINE AREA

The Severnaya Dvina is rightfully considered one of the largest rivers in Russia’s European North and is the main catchment for fisheries in the Arkhangelsk Region. Its lower course is under enormous pressure from numerous pollution sources located along its tributaries and in the estuary. This situation leads to changes in fish habitat conditions, their species diversity, as well as biological parameters, population structure, population dynamics, and stock. This article presents the results of a study of the fish population in the estuarine region of the Severnaya Dvina in 2019 by classical ichthyological research methods using passive (stake nets) and active (draft nets) fishing gear. The species composition and taxonomic diversity of the fish fauna are presented. We determined the affiliations of the fish with faunistic complexes and ecological groups differing in dietary and natural reproduction characteristics (spawning substrates, egg-laying methods, and spawning periods). The economic significance of the fish fauna was assessed, rare and scant fish species listed in the regional Red Data Book were identified. The biological characteristics (length-weight structure, age and sexual composition) of the populations of the main commercial fish species are described. The dietary habits of the two most important species groups, coregonids (whitefish) and cyprinids (bream), are considered. The fish species diversity in the Severnaya Dvina estuary is quite high. The list totals 36 fish species. The biological characteristics of the fish were found to be within the average range for the given species. The commercially important whitefish and bream are benthos feeders (potential competitors for food). But the tension of this competition is reduced due to their different dominant feed items.

Biodiversity in the Cipeles River, Sumedang Regency, West Java Province, Indonesia


 This study aims to determine the diversity of fish species and to analyze the condition of water quality in the Cipeles River, Summedang Regency, West Java Province, Indonesia. The research was conducted for one month. The research method used was census with purposive sampling technique. The sampling period is four times a week. Analysis of the data used in this study is the composition of fish species, relative abundance, diversity, and water quality with quantitative descriptive data analysis. The results showed that the fish caught were baung (Mystus cavasius), singaringan (Mystus singaringan), tilapia (Oreochromis niloticus), hampala (Hampala macrolepidota), paray (Rasbora aprotaenia), genggehek (Mystacoleucus marginatus), lalawak (Barbonymus balleroides), and and julung-julung (Dermogenys pusilla). The fish diversity index value 0,85 – 0,89 was categorized as low with the highest relative abundance of genggehek fish (Mystacoleucus marginatus) at stations I and III, and lalawak fish (Barbonymus balleroides) at station II. The native fish of the Cipeles River that was able to adapt from 2001 until now is M. marginatus.

Multivariate analysis of abundance and distribution of fish species in coast of Ghana, West Africa

Marine fishes are currently experiencing population decline which has severe repercussions on food security, especially in fishing households. However, without assessing the distribution and abundance of these marine fishes, ensuring sustainable management will become impossible. Therefore, the study aimed at applying multivariate techniques to determine the biodiversity of fishes along the coast of Ahanta West, Ghana. Fish samples were collected daily through experimental fishing from November-December, 2011. Data obtained from the study were analyzed for ecological indices, species diversity, and community structure using PAST and PRIMER v6 software. From the results, Pteroscion peli (19.2%), Galeoides decadactylus (11.7%), and Brachydeuterus auritus (9.0%) were the dominant fishes. Multivariate analysis identified three main assemblages of fishes, at 18%. For the ecological indices, the species dominance index (SDI) ranged from 0.89 to 0.93, which indicated that the fish species were highly dominated by a few species. The Shannon Weiner index (SWI) and Species Richness index (SRI) spanned between 2.64 – 2.92 and 4.43 – 648 respectively, showing high diversity of fish species. It is concluded that the marine environment along the Ahanta West, Ghana is rich in fish species diversity, and hence, there is the need to regulate existing fishing operations for sustainable utilization and conservation of these commercially important fish species.
 Res. Agric., Livest. Fish.9(1): 57-59, April 2022

Importance of pneumatophore fringe-mudflat continuum for an estuary-dependent fish species

ABSTRACT Shallow estuarine habitats are well recognized for providing a positive correlation to the abundance and diversity of juvenile fish species. This has been associated with the hypotheses of refuge from predators and the availability of food. Therefore, this study aimed to evaluate the importance of two adjacent habitats to mangrove fringes (area adjacent to pneumatophore zone and mudflat) as an ecological habitat for Diapterus auratus juveniles. Sampling was carried out in the rainy (January–July 2016) and dry (August–December 2016) periods. This study indicated that D. auratus juveniles did not show significant differences in abundance and biomass between adjacent habitats. However, univariate analyses found there was a significant increase in fish abundance in the dry season, due to influx of young-of-the-year. Further, the size-frequency of D. auratus showed a recruitment pattern recorded between August and January, suggesting a broad spawning period between the end of the rainy season and a recovery period between March and May. There were distinct changes in the diet between seasons for D. auratus, according to the dendrogram of the food eaten by the fish. The combined results from the distribution and feeding ecology suggest a connectivity among adjacent areas, and indicate that both habitats provide critical foraging and refuge habitat for D. auratus in this tropical estuary.

Abundance, Species Diversity, and Conservation Status of Reef Fishes in Dumanquillas Bay, Zamboanga, Philippines

Zamboanga is one of the significant fishing grounds in the Mindanao Region, but little is known about the conservation status of reef fishes, particularly in Dumanquillas Bay, Zamboanga. Thus, this study assessed the abundance, species diversity, and conservation status of reef fishes in the bay. The assessment was conducted within eight sampling stations from May 6 to May 16, 2014. Reef fishes were censused using a line-intercept method. Fourteen thousand fifty individuals and 140 fish species belonging to 30 families were recorded―dominated by the family Pomacentridae. The number of fish individuals was significantly more abundant in Triton Island Station than in other sampling stations, while Muyong Island has the most diverse reef fishes. Almost all species are classified as the least concern category, except for Plectropomus areolatus of Cabog Island, which is under the vulnerable (VU) category. The number of less-valued species was higher than the commercially high-valued species. Therefore, it may indicate the overharvest of the latter group of species. This comprehensive study on reef fishes in Dumangquillas Bay may serve as a reference for fisheries resource management planning or for drafting fisheries policies in the bay.

Fish diversity, community structure, and environmental variables of River Tamas, a tributary of River Ganga, India

AbstractThe Tamas River is a right-bank tributary of the River Ganga, originating from Jhukehi village in Madhya Pradesh and meeting up with the Ganga at Sirsa, Prayagraj, Uttar Pradesh, India. An investigation was carried out in six sites at (Itahara, S1), (Madhavgarh, S2), (Bakiya upstream, S3), (Bakiya downstream, S4), (Chakghat, S5) and (Panasaghat, S6) of the river to document the fish diversity, seasonal variability, and impact of environmental variables on fish species composition during the period 2017 to 2019. Altogether 75 fish species belonging to 54 genera, 23 families, and 10 orders were recorded. Fish species richness at (S1), (S2), (S3), (S4), (S5), and (S6) and was recorded as 9, 39, 38, 13, 61, and 49, respectively. Family Cyprinidae with 31 species contributing 41% was the most dominant family, followed by Bagridae (8%) and Schilbeidae (6.7%). Seasonal variation in fish species richness and diversity indices were observed in the river stretch. Maximum species richness (45) was observed at S5 during monsoon and a minimum (6) at S1 during post-monsoon. As per the International Union for Conservation of Nature categorization, 10 out of 75 fish species recorded from the river were considered to be threatened. Three exotic species, namely Cyprinus carpio, Oreochromis niloticus, and Hypophthalmichthys nobilis, were recorded at some stretches, which may be a concern for native fish diversity. Environmental variables like water temperature, pH, dissolved oxygen, water velocity, and alkalinity influenced the fish community structure. The selected (S1–S6) stretch of the river falls under the category of Slightly Impacted River based on the Shannon Index (H’ >3). The present investigation was the first assessment of rich fish diversity covering the maximum stretch of river, which supports many important and small indigenous fishes for conservation.

Diversity of the ichthyofauna of the rivers of the southern macroslope of the Tarbagatai ridge (Alakol basin, Kazakhstan)

Freshwater ecosystems are among the most diverse ecosystem types. The fish communities of the rivers of the southern slope of the Tarbagatai ridge that flow into the system of the Alakol lakes (Alakol and Sasykkol) are currently poorly studied, with the exception of the Emel River. The analysis of literary sources up to the beginning of the 21st century is carried out and the results of our own research are presented. Catching and biological analysis of fish were carried out according to the standard method. The composition and biological parameters of mass fish species in the Karakol, Urzhar, Katynsu, and Emel rivers have been studied. Fish community diversity indices according to Simpson and Shannon were calculated. Using the PAST 4.07 statistical program, the species similarity (according to Sørensen) of the ichthyofauna of the studied rivers was analyzed. Analysis of the obtained results revealed a de-crease in the species diversity of fish in all the studied rivers, which numbered from 4 to 9 species. In general, the presence of 15 species of fish belonging to three families was found, while the basis of the list is representatives of the order carp. For 2 years of the study, it turned out that the composition of the ichthyofauna and the frequency of occurrence of fish species in the rivers were not stable. In addition to the Emel and Karakol rivers, the composition of the ichthyofauna consisted only of native species. The diversity of commercial acclimatized species and random invaders that were previously part of the ichthyofauna of the Karakol, Urzhar and Katynsu rivers has decreased.Key words: ichthyofauna, native, alien, fish communities, biodiversity.

Latitudinal variation in diversity and abundance of mesopelagic fishes associated with change in oceanographic variables along 110°E, south-east Indian Ocean

As part of the second International Indian Ocean Expedition, an oceanic transect from 39.5°S to 11.5°S along 110°E in the south-eastern Indian Ocean enabled concurrent oceanographic measurements and sampling of early stages of mesopelagic fishes within the upper 500 m of the water column. Notable oceanographic features along the generally oligotrophic transect included an increase in surface water temperature from 12 to 28 °C from south to north and low salinities at both ends of the transect. High salinity Subtropical Surface Water was evident over the central part of the transect and low dissolved oxygen occurred at depth at the northern end where tropical waters were influenced by the Indonesian Throughflow. Throughout the study region larval fish stages were generally concentrated in the epipelagic zone. Species richness, abundance and diversity of fishes (n = 166 species) increased towards the tropical waters. The families Myctophidae (lanternfishes; 60 species), Phosichthyidae (lightfishes; 2 species) and Gonostomatidae (bristlemouths; 5 species) were numerically dominant. Clustering of integrated abundance data (0–500 m depth) revealed four major fish assemblages along the transect. When linked to oceanographic variables, multivariate multiple regression indicated that surface temperature, surface salinity and dissolved oxygen at 400 m depth provided the best fitting model explaining fish distribution patterns. Where possible, comparisons have been made with early data collected along this 110° E line in the 1960s during the first International Indian Ocean Expedition.

Responses of Hippopotamus amphibius to environmental changes at Bui National Park, Ghana

Many researchers have adopted the use of indicator species to detect changes in the environment and predict future ecological modifications. Irrespective of the popularity of indicator species concept among scientists in recent times, there is less studies on the use of mega semi-aquatic mammals as indicator species, especially in Africa. This study determined the ecological role of Hippopotamus amphibius and how the mammal respond to environmental changes in an aquatic ecosystem, focusing on changes in biological diversity (fish and phytoplankton) and environmental factors (temperature, pH, dissolved oxygen, conductivity, total dissolved solids, hydrogen isotope, and oxygen isotope) by comparing pools harboring H. amphibius and pools without H. amphibius at the Bui National Park, Ghana. The results show that H. amphibius play an important ecological role by indicating high productivity in aquatic ecosystem and serving as influencers of the aquatic food web at Bui National Park. The results found significantly higher concentrations of dissolved oxygen in H. amphibius pools than pools without H. amphibius. Significantly higher diversity of fish and phytoplankton species were recorded in pools with H. amphibius. Common fish species identified during this study include, Oreohromis niloticus, Labeo coubie, Alestes dentex and Labeo senegalensis. Phytoplankton communities were dominated by Chlorophyceae (37.26%), Cyanophyceae (25.21%), and Bacillariophyceae (21.53%). The study results also showed that H. amphibius are sensitive to changes in depth of water, preferring areas with shallow pools. Managerial options for H. amphibius populations require strong support because of their socio-ecological benefits including potential ecosystem effects, increasing fishing and tourism value at the Bui National Park.

The impact of a Reno mattress installation on an adjacent seagrass meadow and its macrofauna in a South African estuary

Armouring of coastlines and the banks of estuaries to protect property against erosion can have a negative impact on natural habitats and their communities. Within estuaries, one of the most threatened habitats is seagrass meadows. The impact of newly installed Reno mattresses on an adjacent Zostera capensis meadow and associated fauna was investigated in the Keurbooms Estuary, South Africa. The impact on Z. capensis was studied by determining percentage cover and the length of blades before and after placement of Reno mattresses. At the impact site, percentage cover and blade length decreased during the installation phase, however, recovered shortly after installation was completed. At the control site no changes in eelgrass percentage cover were noted. Invertebrate and fish species richness, diversity and abundance were compared in the eelgrass meadows before and after the installation. Whilst invertebrate species richness increased significantly after the installation at the Impacted site, there was no significant difference at the Control site. There was also no significant difference in invertebrate diversity and fish species richness and diversity at the Control and Impacted sites before and after installation. This suggests that the installation had no net negative impact at the Impacted site. Within a month of installation, the Reno mattresses were colonised by two invertebrate species (Amphibalanus amphitrite and Littoraria sp.). Although the introduction of Reno mattresses at the study site created a hybrid habitat that continued to provide a habitat for fish and invertebrates, we suggest that the use of these artificial structures should be in combination with natural vegetation (e.g. as a hybrid habitat) and not one that replaces natural habitat. There is limited information regarding the ecological impacts of using Reno mattresses in estuaries and this study provides new information on their ecological efficacy thus providing valuable insights in future coastal erosion control practices.

Workshop report: Diseases of ornamental and laboratory fishes

Ornamental and laboratory fish populations are part of the global trade and can spread pathogens around the world. Laboratory fish are widely used as model for biomedical research, which can be impacted by underestimated health conditions affecting the fish model. The global ornamental fish industry deals with a huge diversity of fish species. High mortality rate often causes significant losses, linked to polymicrobial infections facilitated by stressful conditions compromising host health, although accurate data on ornamental fish trade losses remain difficult to retrieve. Pet fish diseases can spread undetected between artificially recreated ecosystems, posing threats difficult to eradicate once established or when contaminating natural water systems. This 3-hour virtual workshop aimed at highlighting novel aspects of the pathobiology and diagnostics of infectious threats that could be spread through ornamental fishes and impact research using laboratory fish as biological models. In total, 108 participants from various countries all over the world joined this virtual workshop during the EAFP conference live streaming.

Fish stock assessment and potential yield of a reservoir in Benin City, Nigeria

Fish stock assessments of aquatic ecosystems are relevant against the backdrop of over exploitation, fish species extinction and the inadequate management of aquatic resources especially in developing countries such as Nigeria. The study specifically examined the fish stock assessment and the potential fish yield of the Ikpoba reservoir in Benin City, Nigeria. A total of 903 fishes were captured from the reservoir with individual abundance ranging from 18 (1.99 %) for Epiplatys sexfasciatus to 286 (31.67 %) for Synodontis clarias. A total of 15 fish species belonging to 8 families were identified while the dominant fish species were S. clarias, Hemichromis fasciatus and Marcusenius psittacus. A total of 11 fish species were identified as rare in this study. The Ekiuwa station of the reservoir was the richest species-wise (d= 6.45) while the Midpoint station had the greatest general diversity of fish species (H= 1.42). There was a more even spread and distribution of fish species at the Midpoint station (E= 1.00) while the commonest fish species were most frequent at the Okhoro station (C= 1.62). In this study, the Condition Factor ranged from 1.00 for M. psittacus to 5.78 for Gnathonemus abadii. The potential fish yield index of the reservoir was low due to a low nutrient content and ranged from 17.7 in the dry months to 23.13 in the wet months. It was advocated that the Ikpoba reservoir must be continuously monitored in order to ensure that fish species composition and diversity do not reach critical limits.

Influence of seascape spatial pattern on the trophic niche of an omnivorous fish

AbstractHabitat fragmentation of submerged aquatic vegetation (SAV) transforms the spatial pattern of seascapes by changing both the total area and spatial configuration of the habitat patches. The ecological effects of SAV seascapes are most often assessed using metrics of biological community composition (e.g., species and assemblage changes). We know considerably less about the effects of seascape structure on ecological processes such as food web function and energy flow. Here, we assess the difference in the trophic niche of Pinfish (Lagodon rhomboides, a generalist omnivore) across a spatial gradient of SAV from continuous to highly fragmented seascapes in Biscayne Bay (Miami, Florida, USA). The Bay seascapes are influenced by freshwater management practices that alter the distribution of SAV habitat and fish species abundance, diversity, and community assemblage. We combined SAV seascape maps with stable isotope and hypervolume analyses to determine how trophic niche size and overlap varied with changes in the seascape. We observed similar resource use across the seascape, but trophic niche size increased in more fragmented SAV seascapes, suggesting diversification of trophic roles and energy flow pathways. Pinfish collected from more continuous SAV habitats had smaller trophic niche size and higher trophic levels. Both trophic response metrics manifested a threshold response that depended on distinct SAV spatial characteristics (amount vs. spatial configuration) and environmental conditions. Our results suggest that habitat fragmentation of SAV seascape structure has ecological implications that could affect energy flow with cascading consequences for food web stability and ecosystem functioning.

The role of free-flowing tributary rivers in the maintenance of genetic diversity of a migratory fish species living in a river fragmented by dams

The role of free-flowing tributary rivers in the maintenance of genetic diversity of a migratory fish species living in a river fragmented by dams

Keanekaragaman Jenis Ikan Di Perairan Rawa Dogamit Taman Nasional Wasur Merauke

Dogamit Swamp is one of the swamps in the Merauke Wasur National Park, which stores an abundant diversity of fish and biota. This study aims to examine the diversity of fish species in the waters of Rawa Dogamit. The research was conducted from July to August. The method of data collection was by determining 3 locations of observation stations, at each station an identification of all species and their environmental factors was then linked to the Diversity index, Abundance Index, Evenness Index, and Dominance. The results obtained from the study are that there are 15 species of fish, which have the highest abundance of Betik (Anabas testudineus) by 35.74% and the lowest is the Moon Fish (Megalops cyprinoides) by 0.05%. Measurement of the Diversity index is categorized as moderate, whereas for the Evenness index is categorized high at stations I and II, while station III is categorized as moderate. For the measurement of the Dominance Index, it is categorized as low or not dominant. It was concluded that there was a significant relationship between the diversity, evenness and dominance index with environmental parameters both for the survival of fish in Rawa Dogamit waters.Key Words: Diversity; Fish; Dogamit Swamp

Diversity Study of Freshwater Fishes in Manimala River, Pathanamthitta, Kerala, India

The present study deals with the species diversity of fishes in Manimala River with reference to Eraviperoor region, Pathanamthitta, Kerala, India. The Manimala River forms the northern and north-western boundary and Varattar (a branch of river Pamba) forms the southern boundary of the study area. The wetlands (mainly paddy fields) consist of 18 small to medium-sized water bodies functioning as a water source for agriculture. A chain of canals connects many of them in the lower areas while the remaining ones get interconnected during monsoon floods during which the movement of fishes from rivers to other water bodies takes place. These small water bodies are extremely significant for the preservation and sustenance of the biodiversity of fishes. 24 species belonging to 12 families and 5 orders were collected and identified. This includes10 species from the family Cyprinidae, 3 species from the family Channidae, 2 species from family Cichlidae, and 1 species each from families Hemiramphidae, Belonidae, Anabantidae, Osphronemidae, Heteropneustidae, Claridae, Siluridae, Tetraodontidae, and Ambassidae.

Analysis of Optimal Harvest and Management of Capture Fishery of Lake Ziway, Central Ethiopia

Even if there is fluctuation in fish species diversity and relative abundance of the species, Lake Ziway provides numerous environmental and/or ecosystem services. Despite to its importance, the Lake faces numerous threats because of its public good characteristics. Following the exponentially increased demand for fishes and the resource being public good, magnificent number of individuals are participated in capture fisheries in order to secure their livelihood. Free access to the fisheries, illegal fishing gears and environmental degradation are among the main reasons of decline in fish species and degradation of the Lake. From the current stock assessment survey, the study showed decline in biomass of fish over time. These negative trends in the Lake Ziway fisheries and poor water quality led to loss of livelihoods of many households who are directly or indirectly dependent on the Lake. Therefore, management of Lake Ziway fishery becomes very essential to manage the resource efficiently in a way that maximize fishers present and future benefits otherwise, the fish resource will disappear in the near future. Concerning management practices, most of the fishery regulations in this Lake put emphasis on the restriction of fishing gear, but the application of this instrument with its restrictions is almost zero. Moreover, Individual Transferable Quotas (ITQs) foster greater transparency and accountability for the management and enhancement of fishery resources by quota owners. In this regard, since it generates a sense of ownership and its versatility in providing a stable and productive market, ITQs are more effective than gear restrictions and in fact, it has major social benefits by controlling overharvesting. Due to this, to ensure the nutritional and food security of the country currently and in the near future, there is a need to enforce fishing gear restriction and set ITQs. Furthermore, there must be strong effort on studying the current stock of fish, and numbers of legal and illegal fishers to set Individual Transferable Quotas (ITQs) and Total Allowable Catch (TAC) for sustainable fishery management of Lake Ziway. Keywords: Ziway, capture fisheries, Individual Transferable Quotas, Total Allowable Catch, sustainable fishery management DOI: 10.7176/JESD/13-2-03 Publication date: January 31 st 2022

Peces de la región de la Amazonía Colombiana: composición de especies de los sistemas fluviales del bioma de selva húmeda

Abstract The Colombian Amazon region is part of the Neotropical rainforest (humid forest biome) covering an area of 483,163 km2 and includes tributaries of both the Amazon and Orinoco River basins. The aquatic ecosystems found there include: rivers and alluvial plains originating in Andean headwaters, on eroded soils of tropical forests in the lowlands, and Guiana Shield formations, comprising a dense fluvial drainage network in the lowlands, with Paleogene/Neogene geological formations (terra firme streams in higher places that don’t usually flood) and Paleozoic (shield streams); and Andean and Guiana Shield streams above 200–250 m a.s.l. We present here an exhaustive compilation of published information, supported by fish collections, consisting of a list of 1104 species distributed in 375 genera, 53 families, and 16 orders. We include occurrence data of these species in each sub-basin. The presence/absence species matrix was analyzed using a dendrogram and non-metric multidimensional scaling (NMDS) analysis to identify patterns of similarity between basins and sub-basins. We evaluated species composition between basins and among the different geological origins using PERMANOVA. The dendrogram shows co-occurrences of 404 species in the two basins. It also shows two clear groupings of the sub-basins of the Amazon (except Guainía-Negro drainages) and those of the Orinoco. Within the Amazon Basin, there are two nodes according to the geological origin: systems of Andean origin and those of the lowlands. The dendrogram results are consistent with the NMDS analysis, which shows a clear grouping according to the connectivity of the basins; the Guainía-Negro is included in the Amazon basin. Species distribution patterns were supported by the PERMANOVA, and differed significantly between basins (F = 4.3, R = 0.26, P = 0.003) and geological origin (F = 3.6, R = 0.23, P = 0.003). The number of species in this study represents almost a fifth of the ichthyofauna of the Neotropics and about a third of that of the Amazon River basin; clearly supporting Colombia’s status among the countries with the greatest diversity of freshwater fish species of the planet. We include here a significant number of new records (75 spp), provide a first approximation of the distribution patterns, and a framework for future biogeographical studies.