Orinoco basin

The chocolate talking catfish, Acanthodoras cataphractus, is a doradid catfish from the northern Amazon basin and Atlantic drainages of the Guianas. It is most often exported as bycatch among Platydoras armatulus and is sold under the same trade names as A. spinosissimus, which has pale blotches on the back between the dorsal and caudal fins where this species has pale lines or no markings. Largely nocturnal and gregarious, it is best kept in a group of at least four.

The big-eyed cachorro, Acestrorhynchus falcirostris, is a large predatory acestrorhynchid from northern Amazon drainages and the Orinoco. The two dark body stripes of the A. nasutus group appear only in its juveniles, and at 320 to 350 mm SL it grows far larger than the other members. A black fringe to the rear of the operculum gives it a 'collared' look. It needs open water, and a group must be of comparable size because acestrorhynchids are cannibalistic.

The pike tetra, Acestrorhynchus microlepis, is a predatory acestrorhynchid from northern Amazon drainages and the Orinoco. It also occurs in coastal rivers of Guyana, Suriname and French Guiana. A member of the A. microlepis group, it has a small blackish spot behind the gill cover and is separable from the very similar A. grandoculis only by counts. It tends to take smaller prey such as tetras, and acestrorhynchids are cannibalistic, so a group must be of comparable size.

L147 is an undescribed Ancistomus species, a suckermouth catfish from tributaries of the middle Río Orinoco in Venezuela and the lower Río Meta in Colombia. Some reports suggest it occurs further up the Meta system, around Villavicencio, some 600 km upriver. It spawns in caves with the male responsible for brood care, and has been bred regularly in aquaria.

The striped headstander, Anostomus anostomus, is an anostomid from the Amazon and Orinoco river systems in Peru, Brazil, Venezuela and Guyana. It lives along rocky shores of fast-flowing rivers, grazing algae and small invertebrates from the rocks. Although it shoals in nature, it is very quarrelsome with conspecifics when only a few are kept, so it is best kept singly or in a group of 6 or more in a larger tank.

The gold-striped headstander, Anostomus ternetzi, is an anostomid from the Río Orinoco system and coastal Guyana, Suriname and French Guiana. It lives in rocky areas at the edge of fast-flowing rivers and streams, grazing algae and small invertebrates. Like A. anostomus, it is quarrelsome with conspecifics when only a few are kept. Its distribution in Brazil is unclear, with patchy records from the Araguaia and Xingu basins.

The redspot dwarf cichlid, Apistogramma alacrina, is from the Río Guaviare (Orinoco) and Río Orteguaza (Amazon) drainages in Colombia. It differs from all other described members of the genus in having dark blotches at the dorsal and ventral base of the pectoral fins. Three very similar fishes coded A106, A107 and A108 may or may not be conspecific with it, since they show some differences in colour pattern and morphology.

Apistogramma hoignei is a dwarf cichlid from the Río Orinoco basin in Venezuela, including the Apure, Arauca and Caura drainages. It is also known from much of the lower Orinoco mainstream. Coded A116 under the DATZ system, it has similar-looking, possibly conspecific populations referred to as A117 or A118, and inhabits slower-moving tributaries, backwaters and creeks where leaf litter collects.

Apistogramma hongsloi is a dwarf cichlid from the Río Vichada and middle Río Meta basins in Colombia and the middle Orinoco in Venezuela. Coded A110 under the DATZ system, it has similar-looking, possibly conspecific populations referred to as A111 to A115 depending on locality. It lives in small tributaries and still waters, and males grow to 55 to 60 mm and females to 40 to 45 mm.

Apistogramma macmasteri is a dwarf cichlid known only from the Río Guaytiquía and Río Metica basins in the upper Río Meta system, Colombia. Coded A120 under the DATZ system, it has a similar-looking, possibly conspecific population referred to as A122, and A121 is the ornamental 'red' form. Captive-raised fish are the recommended choice for the community aquarium.

Apistogramma sp. 'breitbinden' is an undescribed dwarf cichlid from the upper Rio Negro in Brazil, the Venezuelan Orinoco and the Inirida in Colombia. The German name means 'broad-banded' and refers to the uniformly broad suborbital stripe of males. Known in the hobby for several decades, it is often imported as bycatch among shipments of wild-collected A. iniridae, and some populations carry the DATZ codes A164, A165 and A167.

The ruby tetra, Axelrodia riesei, is a tiny characid known only from the upper Río Meta basin in Colombia, part of the Orinoco system. It is less often seen in the hobby than A. stigmatias, presumably because of its remote, restricted range, and differs from it in its deeper body and red colour, which can fade after a period in aquaria. It is said to inhabit blackwater environments, and its small size and somewhat specialised requirements make it a poor community fish.

Known as L239 before description, Baryancistrus beggini is a small loricariid from the Orinoco and lower río Guaviare in Venezuela and Colombia. Its body and fins are uniformly black to brownish with a turquoise to bluish sheen. Placement in Baryancistrus is tentative. Territorial with conspecifics but somewhat delicate, it is not recommended for the general community aquarium.

The green phantom pleco, Baryancistrus demantoides, is a suckermouth catfish known only from where the río Ventuari meets the Orinoco in Venezuela. It closely resembles Hemiancistrus subviridis, which lives alongside it, and both have been marketed as L200. B. demantoides is the less common and more expensive of the two, sometimes sold as 'L200 high-fin' or 'L200a' for its longer dorsal-fin spine. Males become increasingly intolerant of conspecifics as they age.

The Orinoco eartheater, Biotodoma wavrini, is a geophagine cichlid from the Orinoco and rio Negro basins of Venezuela, Colombia and Brazil. One natural habitat is the Río Cinaruco, a low-nutrient blackwater tributary of the Orinoco. It can be told from B. cupido by its noticeably elongate body and a dark flank blotch on or below the upper lateral line. Unless breeding it is surprisingly peaceful, and trade populations include 'Cuao', 'Orinoco', 'San Antonio' and 'Sipapo Ventuari'.

The striped pike 'characin', Boulengerella lateristriga, is a ctenoluciid from the rio Negro basin and parts of the upper Río Orinoco. It appears limited to black water rivers and tributaries, where the water is stained darkly with humic acids and the pH can be as low as 3.0 or 4.0. A thin dark stripe from the rear of the eye to the caudal peduncle and dark crossbars on the caudal-fin lobes separate it from the similar B. maculata. It grows to 258 mm SL.

Boulengerella maculata is a pelagic ctenoluciid found throughout much of the Amazon, Orinoco and Tocantins river systems. Colour pattern varies considerably, with some specimens much paler than others, and this may be correlated with water type. Random dark spots on the upper body, and a dark stripe only behind the eye when one is present, separate it from the similar B. lateristriga. It reaches 329 mm SL and needs an aquarium with base dimensions of 240 by 90 cm or more.

The discus tetra, Brachychalcinus orbicularis, is a deep-bodied characid generally considered endemic to coastal watersheds of Guyana and Suriname. Recent records suggest it, or a similar congener, may also occur in the Orinoco and Negro drainages. The genus is often referred to collectively as 'silver dollar tetras', and although B. orbicularis is normally said to be the species in the trade, identification is challenging.

Brochis delphax, long known as Corydoras delphax, is an armoured catfish from the Río Inírida and other parts of the upper Orinoco basin in Colombia. The name is used often in the trade, sometimes for misidentified congeners, while B. delphax itself is often traded as C. punctatus. A relatively elongated snout, body spots that fade in adults and spots in the caudal fin are said to separate it from B. agassizii, Hoplisoma brevirostre and others.

The blackwing hatchetfish, Carnegiella marthae, is a small freshwater hatchetfish from the upper Orinoco in Venezuela and the rio Negro in Brazil. It appears to be a stenotypic inhabitant of blackwater, found in igapó and igarapé habitats with overhanging vegetation and leaf litter. Very peaceful but small and timid, it is best kept in a group of 10 or more with similarly sized, peaceful fishes.

The marbled hatchetfish, Carnegiella strigata, is a hatchetfish from the Amazon and Orinoco basins and coastal rivers of Guyana and Suriname. Popular in the hobby, it is collected for the trade mostly in the rio Negro basin in Brazil. Its larger size and dark, marbled pattern set it apart from congeners, though the pattern varies and the wide range may be open to question. It appears to live only in blackwater.

The striped bulldog pleco, Chaetostoma formosae, is a suckermouth catfish from piedmont streams of the upper Meta and Guaviare systems in Colombia. The commonest member of the genus in the hobby, it is still misidentified as C. thompsoni and sold under several names and L-numbers. An obligate inhabitant of fast-flowing headwater streams, it needs clean, well-oxygenated water with strong flow and does best in a dedicated species set-up.

The Amazon puffer, Colomesus asellus, is a freshwater puffer found throughout much of the Amazon basin, with records north to Guyana and Venezuela. Also traded as the South American puffer or 'SAP', it is told from congeners by a transverse row of dermal flaps across the chin. It lives mostly in well-oxygenated river habitats, is intolerant of organic waste, and forms loose aggregations, so a group of 6 or more is best, away from the general community.

Copella eigenmanni is a small lebiasinid from the Orinoco system in the llanos of Colombia and Venezuela, including the Meta, Caroní and Apure. It turns up in the trade from time to time among wild-caught fishes from the Orinoco basin. Colombian populations were formerly called C. metae until Zarske (2011) synonymised the two. A broad dark stripe runs from the snout to the eye, and the eggs are laid among vegetation and guarded by the male.

Cynodon gibbus is a cynodontid from much of the Amazon basin, the middle and lower Orinoco, and the Rupununi River in Guyana. A pelagic fish of main river channels and larger tributaries, it grows to around 280 mm SL. It is rare in the trade but arguably more suitable for the home aquarium than some of its better-known relatives, given its size and relatively docile behaviour. Being easily dominated, it is best kept alone or with similarly sized, non-aggressive fishes.

Geophagus abalios is a cichlid from black and clear water tributaries of the río Orinoco in Venezuela, across the Llanos and south to the Casiquiare. One of the more commonly-traded members of the genus, it is rarely sold under the correct name and usually misidentified as G. altifrons or G. surinamensis. Juveniles are available cheaply because it is one of the few Geophagus bred commercially. Vertically split anterior flank bars separate it from the very similar G. brokopondo.

Geophagus dicrozoster is a cichlid from tributaries of the río Orinoco in Venezuela, extending to the Casiquiare and the headwaters of the Negro. Commonly traded but rarely under the correct name, it is usually sold as G. altifrons or G. surinamensis, and it is one of the few Geophagus bred commercially. Seven flank bars, the fourth and fifth meeting in a 'Y', and a relatively elongate profile identify it. It appears restricted to acidic blackwater.

Geophagus taeniopareius is a cichlid from the Venezuelan upper Río Orinoco, recorded from tributaries including the Caura, Cataniapo and Ocamo. Known in Germany as the 'Wangenstrich-Erdfresser' (cheek-stripe eartheater), it has been in the hobby since the late 1970s. A dark stripe runs from the eye to the corner of the opercle. It is markedly more aggressive than most congeners and spawns on the substrate.

The slate cory, Hoplisoma concolor, long known as Corydoras concolor, is an armoured catfish restricted to parts of the Orinoco river system in western Venezuela. Its uniformly greyish colour pattern sets it apart from congeners, along with a deep body, large eye and relatively long dorsal-fin spine. Mature males develop an extended dorsal fin.

The salt and pepper cory, Hoplisoma habrosum, long known as Corydoras habrosus, is a tiny armoured catfish from left bank tributaries of the upper Orinoco in Colombia and Venezuela. Most records come from the Río Apure watershed in the Llanos, where it apparently favours lagoons, streams, inundated forest and grassland with little flow. Also called 'dainty cory' and 'Venezuelan pygmy cory', it has 2-3 dark markings along the side of the body, against 4-5 in the similar H. cochui.

The false bandit cory, Hoplisoma melini, long known as Corydoras melini, is an armoured catfish from tributaries of the rios Negro, Caquetá and Orinoco in Brazil and Colombia. Its oblique dark bar along the back splits into two above the caudal peduncle, a feature shared only with H. davidsandsi, from which the dark markings on its flanks separate it. The rio Tiquié population is known in the hobby as 'C084', and a similar, slightly larger form from Peru as 'C085'.

The bandit cory, Hoplisoma metae, long known as Corydoras metae, is an armoured catfish endemic to the upper Río Meta, an Orinoco tributary in eastern Colombia. It appears to be absent from the lower Meta and has not been recorded in Venezuela. Also called 'masked' or 'Meta' cory, it has an oblique dark bar on the rear of the body that ends at the caudal-fin base without splitting, and no other dark markings on the body.

The purple tetra, Hyphessobrycon metae, is a characid endemic to the middle Río Orinoco watershed in Colombia and Venezuela. Also known as 'Río Meta tetra', it is often misidentified, and H. peruvianus has repeatedly appeared under its name. The dark band on the caudal peduncle, without a broad dark band along the lower body, separates it from H. peruvianus and H. loretoensis.

The green line lizard tetra, Iguanodectes spilurus, is a characin found throughout the Amazon, Orinoco, Essequibo and Tocantins river systems. The most widespread Iguanodectes species, it has also been called the 'slender', 'spindle' or 'iguana' tetra, and differs from its congeners in its translucent dorsal and anal fins, lack of a red lateral stripe and prominent dark caudal-fin marking. It is sensitive to poor water conditions.

Isorineloricaria acuarius is a suckermouth catfish from the Apure and middle Orinoco drainages in the Venezuelan Llanos, where it lives on sandy runs in whitewater rivers. Traded as L093 and L195, the blue fin thresher pleco, it was sold as Hypostomus villarsi until it was described in 2016. I. villarsi is a different fish from the Lake Maracaibo basin, with a sharp ridge on each side of the head where I. acuarius has a rounded one.

Leporellus vittatus is an anostomid with a huge natural range across the Amazon, Paraná-Paraguay, São Francisco and Orinoco river systems. Unlike most anostomids it is adapted to a benthic existence in flowing water and spends most of its time on or around the substrate. Occasionally exported, it requires quite specialised conditions, an aquarium of at least 210 by 60 cm and ideally a group of six or more.

The lipstick leporinus, Leporinus arcus, is an anostomid from the Orinoco, Essequibo and upper Courantyne basins in Venezuela and the Guianas. It grows to 250 to 300 mm and needs an aquarium with base dimensions of at least 210 by 60 cm.

Leporinus brunneus is an anostomid from the rios Madeira and Negro in Brazil, the Orinoco in Venezuela and Colombia, and the Casiquiare canal. The largest officially recorded specimen measured 256 mm, and an aquarium with base dimensions of at least 210 by 60 cm is needed.

The red phantom tetra, Megalamphodus sweglesi, is a small characid endemic to the upper and middle Río Orinoco watershed in Colombia and Venezuela. It apparently favours minor tributaries, oxbows and flooded forests, and in Venezuela is often found in morichals. Bred commercially in several countries, it has been traded in more than one colour form, and Zarske (2014) concluded that the particularly red form sold as 'red' or 'var. rubra' is conspecific.

The hockeystick pencilfish, Nannostomus eques, is a lebiasinid from the central and upper Amazon, the Orinoco drainage and rivers of Guyana. It swims at an oblique angle, a trait shared only with N. unifasciatus among congeners, and is also known as the 'rocket', 'diptail' or 'tubemouth' pencilfish. Genetic research on rio Negro populations raises the possibility that the species may be a complex of cryptic taxa.

The dwarf pencilfish, Nannostomus marginatus, is a lebiasinid of Guyana, Suriname and the middle-to-lower Amazon in Peru, Colombia and Brazil. Enduringly popular, it lacks the red body colour of males of the related N. mortenthaleri and N. rubrocaudatus, showing three dark lateral stripes with no red or purple between them. Colour varies between populations, and its small size and timid nature make it a poor community fish.

The greenstripe pencilfish, Nannostomus marilynae, occurs in the rio Negro in Brazil and the Río Vichada in the upper Orinoco basin, Colombia. Also known as 'Marilyn's pencilfish', it is rarely traded in numbers and more often seen as bycatch among shipments of Paracheirodon axelrodi. It most resembles N. minimus, but males lack the highly modified anal-fin of that species.

The bronze cory, Osteogaster aenea, long known as Corydoras aeneus, is an armoured catfish described from Trinidad and accepted to occur across much of South America. That range looks more like a complex of similar, distinct species than a single one, and fish from outside Trinidad are of uncertain identity. Aquarium fish are almost all commercially farmed, and the names C. schultzei and C. venezuelanus are routinely misapplied to them.

The cardinal tetra, Paracheirodon axelrodi, is a small characid from the rio Negro and Orinoco drainages of Brazil, Colombia and Venezuela. Immensely popular in the hobby, it is now commercially bred on a large scale, but a significant proportion of trade fish are still wild caught or come from community-led projects such as Project Piaba. Rio Negro and Orinoco populations differ in colour pattern, and wild fish are less tolerant of deteriorating water conditions than commercially-produced ones.

The green neon tetra, Paracheirodon simulans, is a small characid from the rio Negro and Orinoco drainages of Brazil, Colombia and Venezuela. An exclusive inhabitant of blackwater, it lives only in the upper, terra firme reaches of tributaries and is sometimes traded as 'false neon tetra' or 'blue neon tetra'. A greener lateral stripe that extends to the caudal-fin base and duller red flanks separate it from P. innesi and P. axelrodi.

The black darter tetra, Poecilocharax weitzmani, is a crenuchid recorded from Brazil, Colombia, Peru and Venezuela. It has been collected from the upper Río Negro, Río Orinoco and Río Solimões drainages. Also traded as 'Black Morpho' tetra, it requires specialist care and is notoriously reluctant to accept dried foods. Unlike most small characids it does not form schools, and males are aggressively territorial towards one another. The Peruvian populations may apparently represent an undescribed species.

The black spot piranha, Pygocentrus cariba, is restricted to the Río Orinoco basin in Colombia and Venezuela. Many of its habitats lie within the llanos, and it has been recorded from river channels, tributaries and floodplain lakes, many of them acidic blackwater environments. Specimens over 100 mm SL have a large humeral spot and few spots on the body, which separates it from P. nattereri. It is best maintained alone.

The threespot eartheater, Satanoperca daemon, is a cichlid from the rio Negro, Casiquiare and upper Orinoco systems in Brazil, Venezuela and Colombia. It is mostly observed in acidic, mineral-poor blackwater. Relatively common in the aquarium trade, it is by no means easy to maintain, needing particular attention to space, diet, water quality and chemistry. Two dark blotches on the flank separate it from the similar S. lilith, which has only one.

Satanoperca mapiritensis is an eartheater cichlid native to the lower Río Orinoco basin in northern Venezuela, including the ríos Caura and Caroní. Uncommon in the aquarium trade, its name is frequently misapplied to S. leucosticta and similar, unidentified forms. Adults have white spots and vermiculations on the head, most intense on the operculum, and pale orange lips. Genetic research suggests it may turn out to be conspecific with S. jurupari and S. rhynchitis.

Goulding's piranha, Serrasalmus gouldingi, is a deep-bodied piranha from the rio Negro drainage in Brazil and the Casiquiare system in Venezuela. It occasionally appears in the ornamental trade, sometimes as 'blue tiger piranha'. The eye is bluish or coppery, the body carries vertically-elongate dark spots and the caudal-fin has a blackish basal band. Its native rivers are acidic, mineral-poor blackwater, and it is best kept alone.

The spotfin hatchetfish, Thoracocharax stellatus, is the most widespread neotropical hatchetfish, recorded from much of South America. It is told from its only congener, T. securis, by a prominent dark spot in the dorsal fin, and is sometimes traded as 'platinum hatchetfish'. It feeds almost entirely on insects, and a tightly fitting cover is needed because it can clear several metres in one jump.

The saddle cichlid, Aequidens tetramerus, is a cichlid found across much of northern South America, from the Amazon and Orinoco basins to the Guianas. The type species of its genus, it occurs in several colour forms, and fish from Ecuador and Peru are sought after for the red or orange colouration on the lower head and belly. As currently recognised it is likely to represent a group of related fishes, some of which may be described as distinct species.

The blue acara, Andinoacara pulcher, is a cichlid native to Trinidad and Tobago and parts of Venezuela. It occupies a variety of habitats, from murky still waters to clear streams. A mainstay of the hobby for many years, it is one of the easiest substrate-spawning cichlids to breed. Captive breeding has narrowed the gene pool, so most fish in the hobby are pale imitations of wild ones, and some are hybrids with related species. It was previously known as 'Aequidens' pulcher.

Boulengerella cuvieri is a pelagic ctenoluciid characin from much of the Amazon basin, the Río Orinoco and coastal drainages of the Guianas. The largest officially recorded specimen measured 675 mm, but it appears to grow larger, possibly beyond 800 mm. Given that size and its natural behaviour it is largely unsuitable for the home aquarium. Its entire dorsal-fin base lies ahead of the anal-fin origin, a character shared only with B. lucius and B. xyrekes among ctenoluciids.

Boulengerella lucius is a large, pelagic ctenoluciid from the central Amazon region in Brazil and the Río Orinoco in Venezuela. Named for its resemblance to the northern pike, it grows to 420 mm and is largely unsuitable for the home aquarium. Juveniles and subadults are sometimes available in the trade, often misidentified as B. maculata. Dark patches between the median caudal-fin rays and random dark spots on the lower flanks separate it from B. cuvieri and B. xyrekes.

The slobbering catfish, Brachyplatystoma platynemum, is a large migratory pimelodid catfish from the Amazon and Orinoco basins. The name refers to its relatively thick barbels, which give the impression that the fish is drooling. It travels considerable distances along deeper, flowing channels, and sexually mature adults have been observed in the upper rio Madeira basin, some 3000 km from the estuary. It grows to 1000 mm SL.

Corydoras simulatus is an armoured catfish known only from the upper Meta watershed in Colombia. It can be identified from most similar-looking congeners by its pair of small rictal barbels. The colour pattern varies considerably with collection locality and some forms have been misidentified as other species, while fish with a dark marking on the sides are sometimes referred to as Corydoras sp. 'olga'.

Hemiancistrus subviridis is a suckermouth catfish from the upper Orinoco and Casiquiare drainages in southern Venezuela, where it lives in cracks between granite rocks in flowing water. Known in the hobby as the green phantom plec, it shares the code L200 with Baryancistrus demantoides. Only B. demantoides has a membrane joining its dorsal and adipose fins. It looks very like L128, the blue phantom plec, and along the Orinoco the two fish grade into each other in colour.

The payara, Hydrolycus armatus, is a large, predatory dogtooth characin from the eastern Amazon, the Orinoco and the Essequibo in Guyana. Given its eventual size and natural behaviour it probably should not be considered a home aquarium subject at all, though juveniles are sometimes sold. It is regularly confused with the smaller H. scomberoides, and no other member of the genus has white margins to the anal and caudal fins.

Hydrolycus tatauaia is a large, predatory dogtooth characin from the lower and central Amazon, the upper Orinoco and coastal drainages of Guyana. A pelagic species of flowing main river channels, it performs long upstream migrations to spawn. Its adult size and natural behaviour mean only a handful of private aquarists have the facilities to house it long-term.

Tatia galaxias is a wood catfish from the Orinoco river basin in Venezuela and Colombia, dark with small, round white spots like stars. It is sometimes confused with Tatia intermedia, in which the spots are longer and oval.

Hyphessobrycon acaciae is a small tetra known only from streams in the middle and upper Río Guamal, part of the Río Meta system in Colombia. The dark lateral band separates it from most Hyphessobrycon in the Orinoco basin, and it is told from the remaining few by counts of fin rays, teeth and scales. The Guamal drains into the upper Meta, which flows into the Río Orinoco.

The giant bumblebee catfish, Pseudopimelodus bufonius, is distributed throughout northeastern South America, from Venezuela to eastern Brazil. Its range extends from the Lake Maracaibo basin, and it grows to 245 mm SL. The type locality is uncertain but probably Cayenne, French Guiana.