Orinoco

The marbled headstander, Abramites hypselonotus, is an anostomid from the Amazon, Orinoco and Paraguay-Paraná basins in South America. An ecological generalist, it occurs in turbid main river channels, minor tributaries and backwaters, and enters inundated zones during the annual floods. Best kept as a group in a large tank alongside cichlids, characins and catfishes, it may nip long or trailing fins and eat soft-leaved plants.

The lyre tail pleco, Acanthicus hystrix, is a very large loricariid catfish from the Amazon region of Brazil and Peru. A handful of records come from the Orinoco in Venezuela. Juveniles are traded in quite large numbers, but it can reach at least 1000 mm in nature and 500 to 600 mm in captivity, and becomes increasingly belligerent with age. Young fish are easily told from A. adonis by lacking its white to yellowish body spots.

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 red-tailed freshwater barracuda, Acestrorhynchus falcatus, is a predatory acestrorhynchid from the northern Amazon and Orinoco basins. It also occurs in coastal rivers of Guyana, Suriname and French Guiana. Its large humeral spot, shaped like an inverted tear drop, separates it from other Acestrorhynchus. Reaching 250 to 275 mm, it needs plenty of open water, and a group must be of comparable size because acestrorhynchids are cannibalistic.

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.

The manduba, Ageneiosus inermis, is a large auchenipterid catfish found throughout much of South America east of the Andes. At around 470 mm SL it would need an aquarium in excess of 400 x 120 cm as an adult and is largely unsuitable for private aquaria. An obligate carnivore, it can take surprisingly large prey, and the larger Ageneiosus species are often used as food fishes in their native countries.

The duck catfish, Ageneiosus ucayalensis, is an auchenipterid catfish described from Peru and recorded across the Amazon, Orinoco and Guianas. Body patterning apparently varies with locality, and fish from black water habitats, particularly on the Guiana Shield, tend to be darker. Growing to around 290 mm SL and capable of taking large prey, it is safe only with similarly sized catfishes or large pelagic characins, mostly a combination for public aquaria.

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 brevis is a dwarf cichlid from the Rio Uaupés basin in far northwestern Brazil and the Rio Tiquié in southern Colombia. It has also been recorded in the upper Rio Negro and Rio Orinoco, and inhabits slow-moving blackwater streams where the pH can drop as low as 4.0 or 5.0. Coded A168, it is the type species of the A. brevis group, and breeding is not too difficult if very soft, acidic water can be provided.

The cockatoo cichlid, Apistogramma cacatuoides, is a small cichlid from the upper Amazon basin, from the Ucayali in Peru to the Solimões in Brazil. It lives in slow tributaries, backwaters and creeks where leaf litter collects. Numerous line-bred forms such as 'double red' and 'orange flash' are traded, and captive-raised fish suit a community aquarium, while wild fish are best kept alone or with small dither fishes.

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 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 red edge apisto, Apistogramma viejita, is a dwarf cichlid from the upper Meta basin, part of the Orinoco system in Colombia. Many forms of A. macmasteri enter the trade incorrectly labelled viejita. Male A. viejita have a dark top edge to the dorsal fin and A. macmasteri does not. It inhabits shallow, slow-moving shoreline water with abundant riparian and emergent vegetation, often in savannah country.

The gulper catfish, Asterophysus batrachus, is a predatory auchenipterid catfish from the rio Negro in Brazil and the Orinoco in Venezuela. Also called the 'ogre catfish', it hunts in shallow blackwater tributaries, mostly at night. It can consume fishes almost twice its own size and is not recommended for the community aquarium.

The oscar, Astronotus ocellatus, is a large cichlid widely distributed in the Amazon region, recorded from Colombia and Venezuela south to Argentina. It grows to 350 mm SL and typically lives 10 to 20 years, both of which need taking into account before purchase. Most fish on sale come from commercial breeders in Eastern Europe or the Far East, in numerous ornamental strains, and genetic analyses suggest the genus contains additional, morphologically cryptic species.

The two spot astyanax, Astyanax bimaculatus, is a characid ranging from Panama through most of the Amazon and Orinoco basins. It lives in a wide variety of biotopes, from swiftly-flowing rivers and streams to ponds, ditches and reservoirs. The name is currently applied to what is considered a species complex of at least four taxa, and aquarium fish most often arrive as contaminants among shipments of other species.

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 spotted headstander, Chilodus punctatus, is a headstander from much of the Amazon, the western Orinoco and coastal rivers of Guyana and Suriname. Also called the 'checkered headstander', it lives in slow-moving rivers, oxbows and floodplain lakes, and its colour pattern appears to vary with locality. Shy and peaceful, it is sensitive to dissolved organic wastes and should never be introduced to a biologically-immature aquarium.

The keyhole cichlid, Cleithracara maronii, is a small cichlid from French Guiana, Guyana, Suriname, the Orinoco delta in Venezuela and Trinidad. It is told apart from relatives by the keyhole-shaped marking on each side of the body, and is one of few fishes whose generic name derives from its aquarium common name. It inhabits slow-moving blackwater streams, is naturally shy and sensitive to deteriorating water quality, and most fish on sale are commercially farmed.

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.

The spotted splashing tetra, Copella meinkeni, is a small lebiasinid from the central Amazon region, with most records from the rio Negro and Orinoco. It has been widely referred to as C. nattereri in aquarium literature, but lacks that species' dark lateral stripe and has 5-6 rows of bright red spots on the body. The similar C. callolepis is also traded. It inhabits forest streams with tea-coloured water and lays its eggs among vegetation.

The sailfin characin, Crenuchus spilurus, is a crenuchid from much of the Amazon and Orinoco drainages and coastal rivers of the Guianas. The only described member of its genus, it varies considerably in colour pattern and morphology across that range. It lives in tea-stained forest streams, and its timid, predominantly benthic nature means it does not always make an ideal community fish. Males guard eggs laid on the roof of a small cave, often formed from leaf litter.

The twig catfish, Farlowella vittata, is a stick-like loricariid from the Orinoco river basin in Colombia and Venezuela. This is the most common Farlowella in hobbyists' tanks, although much of the literature refers to it as F. acus, which has a shorter, less slender rostrum. It is super sensitive to poor water quality and should only go into an established aquarium with a good biofilm, algae or dried leaves.

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.

Traded as the 'red line lizard tetra', Iguanodectes adujai is a characin from the rio Negro in Brazil and the upper Río Orinoco in Venezuela. It is exported alongside the similar-looking I. geisleri, and differs in lacking the black lateral stripe beneath the red stripe and in having 28 to 34 anal-fin rays (20 to 25 in I. geisleri). It is assumed to live in smaller tributaries containing pristine blackwater.

Iguanodectes geisleri is a characin from the rios Madeira and Negro in Brazil and the upper Río Orinoco in Venezuela. Traded with the similar-looking I. adujai as the 'red line lizard tetra', it differs in having a black lateral stripe beneath the red stripe and 20 to 25 anal-fin rays (28 to 34 in I. adujai). Adult males carry red markings in the pectoral, pelvic, anal and caudal fins.

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.

The striped headstander, Laemolyta taeniata, is an anostomid from the central Amazon basin, also recorded from the Orinoco system in Venezuela. The largest-growing member of the genus, to 288 mm SL, it is rarely seen in the aquarium trade. Something of a habitat generalist, it migrates into flooded forest in the wet season and has been seen in large migratory shoals with Leporinus fasciatus and L. agassizii. Water quality is of the utmost importance, and anostomids are prodigious jumpers.

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 bar-tailed hoplo, Megalechis picta, is a callichthyid catfish widely distributed east of the Andes in Brazil, Venezuela and Guyana. It is recorded from the Amazon, Orinoco and upper Essequibo systems. Previously referred to as M. thoracata, it can be told from that species by a dark vertical bar in the caudal-fin and a longer dorsal-fin spine. Peaceful and hardy, it can even tolerate hypoxic conditions, and the male builds a nest.

The ram, Mikrogeophagus ramirezi, is a dwarf cichlid from the llanos of the Rio Orinoco drainage in Venezuela and Colombia. Among the more popular dwarf cichlids in the hobby, it is produced commercially in huge numbers, and ornamental strains such as 'gold', 'long-finned' and 'balloon' tend to be genetically weak and short-lived. Wild fish are of superior stock but more demanding, and it requires pristine water quality.

The smallest member of its genus, Nannostomus anduzei is a pencilfish from the upper Orinoco in Venezuela and the rio Negro basin in Brazil. Rarely traded in numbers, it is a relatively common contaminant among shipments of wild fishes from Manaus. Males have an intensely red caudal peduncle and anal-fin, and its size and timid nature suit a tank of its own or diminutive tankmates such as Paracheirodon simulans.

The golden pencilfish, Nannostomus beckfordi, is a lebiasinid widely distributed across Guyana, Suriname, French Guiana, Brazil and Venezuela. The type species of the genus and fairly ubiquitous in the trade, it is less demanding than most congeners and a good choice for a newcomer. Many fish on sale are farmed, and wild populations vary in colour pattern, several having been described as species now considered synonyms of N. beckfordi.

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 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 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.

Peckoltia wernekei, also known as L243 and LDA086, is a suckermouth catfish known only from parts of the upper Río Orinoco drainage in Amazonas state, southern Venezuela. Armbruster and Lujan described it in 2016 from the Ventuari drainage. It is sometimes confused with Peckoltia lineola, alongside which it is often exported for the aquarium trade.

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.

Synaptolaemus latofasciatus is a headstander from the upper Orinoco, the Casiquiare Canal and the middle-to-lower Amazon in Venezuela and Brazil. Described from a single specimen and placed in Leporinus until 2011, it was then recognised as the fish described as Synaptolaemus cingulatus. Alternating transverse bands of orange or yellow and dark brown or black run along the entire body, and snout shape and colour pattern vary with locality.

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.

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 piraíba, Brachyplatystoma filamentosum, is the largest catfish of the Amazon basin, also found in the Orinoco and river systems of the Guianas. Adults typically measure 2 to 2.5 m and weigh over 150 kg. In the Amazon only fish over around 160 cm are called 'Piraíba', and smaller ones 'filhote'. It is suitable only for public aquaria and a very small minority of private aquarists.

The gold zebra catfish, Brachyplatystoma juruense, is a large pimelodid from the middle Amazon and Orinoco basins, described from the rio Juruá. Adults have broad dark vertical, oblique or branching bands on a pale yellowish body and grow to at least 600 mm. It is sometimes confused with B. tigrinum, especially when young, but has a much less defined pattern, a deeper body and shorter barbels. It suits only public aquaria and a very small minority of private aquarists.

The dourada, Brachyplatystoma rousseauxii, is a large migratory pimelodid catfish from the Amazon and Orinoco drainages and rivers of the Guianas. Juveniles feed in the Amazon delta, while sexually mature adults are found only in the western Amazon. Some populations cover as much as 5500 km during migration from the delta, the longest known in any freshwater fish, and it is heavily fished during its upstream movement. It grows to 1900 mm SL.

The piramutaba, Brachyplatystoma vaillantii, is a large migratory pimelodid catfish from the Amazon and Orinoco watersheds and rivers of the Guianas. Juveniles feed in the Amazon delta before migrating upstream in massive numbers, when they are subject to intensive capture by commercial and artisanal fisheries. Sexually mature adults have been observed in the rio Caquetá basin, some 3500 km from the estuary. It grows to 1050 mm SL.

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.

Laetacara fulvipinnis is a cichlid from the Orinoco, the Casiquiare and the upper and middle rio Negro in Venezuela and Brazil. Known in the hobby as L. sp. 'orangeflossen' before it was described, it takes its name from the reddish-yellow anal and caudal fins. It has been collected among leaf litter and submerged vegetation in very shallow, soft, acidic blackwater, and grows to around 74 mm SL. A biparental substrate-spawner, it lays its eggs on a solid surface such as a plant leaf.

The biara, Rhaphiodon vulpinus, is a dogtooth characin found from the Orinoco and Amazon basins south to the Río de la Plata in Argentina. The only member of its genus, it grows to 600 to 800 mm and is an obligate piscivore, and it is suitable only for public installations or the very largest private aquaria. Juveniles are seen for sale quite regularly, most often without adequate information on their long-term care.

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.

The green whiptail, Acestridium dichromum, is a small loricariid catfish from the upper rio Negro in Brazil and the upper Orinoco in Venezuela. It is known only from those two basins and the drainages between them, including the Casiquiare Canal.

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.