Guyana

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 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 chocolate talking catfish, Acanthodoras spinosissimus, is a doradid catfish from the northern Amazon basin and the Essequibo in Guyana. Usually exported as bycatch among Platydoras armatulus, it is sold under the same trade names as A. cataphractus, and the most useful difference is the pale blotches on its back between the dorsal and caudal fins. 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 bottlenose catfish, Ageneiosus marmoratus, is a predatory auchenipterid catfish from Guyana, Suriname and the upper Amazon in Peru and Ecuador. Also sold as 'Guyana slopehead', 'dolphin' or 'hammerhead' catfish, it loses much of its black-blotched juvenile patterning as it grows. Surprisingly peaceful with anything too large to swallow, it is active and sometimes skittish, and needs a tank of at least 150 x 60 cm.

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.

The four-eyed fish, Anableps anableps, is a viviparous fish of brackish mangrove coasts in north-eastern South America, from Venezuela to Brazil. Each eye is split horizontally, with two corneas and two pupils, so it can see above and below the water at the same time. It moves in and out with the tides, and in aquaria it needs brackish water, shallow depth and a large surface area, with a group of at least six in a tank no smaller than 150 x 45 cm.

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.

Steindachner's apisto, Apistogramma steindachneri, is a dwarf cichlid from the Essequibo, Demerara and other river systems of Guyana and Suriname. It lives in slower-moving tributaries and streams with leaf litter and submerged wood. The form from the Demerara drainage carries the DATZ code A138, and a very similar fish from the Cuyuni basin in eastern Venezuela (A139) may or may not be conspecific.

The black ghost knifefish, Apteronotus albifrons, is a weakly electric knifefish from the upper half of South America, from Colombia to Paraguay. Usually sold at around 4 inches, it grows to 50 cm and needs a long-term housing plan. Its eyesight is very poor, and it navigates, finds prey and communicates using a weak electric field. In the wild it lives in swiftly flowing streams and rivers over sand.

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 midnight catfish, Auchenipterichthys coracoideus, is an auchenipterid catfish from the Peruvian and Brazilian Amazon and the Essequibo drainage. Also known as the 'Zamora woodcat', it has often been misidentified as A. thoracatus, and the two differ principally in anal-fin ray count. By day it shelters among submerged roots, tree stumps or vegetation in turbid rivers and flooded areas, emerging to feed in open water at night.

The glass tetra, Bario oligolepis, is a characin from northern South America, with populations in Venezuela, the Guianas, Peru and Brazil. One of a handful of species that closely resemble the red-eye tetra, it is seen much less often in the hobby and is also known as the glassy tetra. It inhabits slow-moving rivers, tributaries and floodplain lakes. Very peaceful, it does not compete well with boisterous or much larger tankmates.

The cupid cichlid, Biotodoma cupido, is a geophagine cichlid from much of the Amazon basin, north to the Essequibo in Guyana and south to Bolivia. Also traded as the 'green-streaked eartheater', it varies in colour pattern and shape by locality, and most traded fish come from around Santarém in Pará state. Unless breeding it is surprisingly peaceful. Its relatively compact body and a dark flank blotch above the upper lateral line separate it from B. wavrini.

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.

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 wimpel piranha, Catoprion mento, is a scale-eating fish from Colombia, Venezuela, Guyana, Brazil and Bolivia. Though not a true piranha, it resembles them and is quite closely related to Pygocentrus species. The common name comes from the German 'Wimpel' (banner), after the extensions to the leading dorsal-fin rays in mature fish. Adults are best housed alone, and it is sensitive to poor water quality and to swings in chemistry.

The reticulated driftwood catfish, Centromochlus reticulatus, is a small auchenipterid first known from the upper Rupununi River basin in Guyana. Its secretive, mostly nocturnal habits mean it may have been overlooked elsewhere, and it has been recorded from the rio Preto da Eva near Manaus, Brazil. Sometimes traded as 'purple oil catfish', it is highly gregarious and ideally kept in groups of at least eight.

The pink-tailed chalceus, Chalceus macrolepidotus, is a large characin found throughout northern South America, from Colombia to French Guiana. It inhabits the surface layers of highly oxygenated rivers. Its very large scales tend to fall off during transport, so new imports can be delicate, though once acclimatised it usually proves fairly hardy. It does best singly or in a group of more than six, since smaller groups tend to scrap.

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.

The banded puffer, Colomesus psittacus, is a large puffer of coastal waters from Colombia and Venezuela through the Guianas to northeastern Brazil. It also occurs in Trinidad and Tobago and the Caribbean islands, and inhabits mangrove swamps, estuaries and the lower reaches of rivers. Growing to 290 mm SL, it is the largest of its genus and has six dark bands across the back. Likely to prove aggressive in all but the largest systems, it is not a popular aquarium fish.

Copella carsevennensis is a small lebiasinid from coastal river systems in Guyana, Suriname, French Guiana and Amapá state, Brazil. It appears in the trade from time to time among wild-caught fishes from the Guianas. Zarske (2011) separated it from C. arnoldi, partly because it lays its eggs among submerged vegetation and not out of the water, though Mol (2012) considers the two synonymous.

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.

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.

The bucktooth tetra, Exodon paradoxus, is a scale-ripping characin widespread in the Brazilian Amazon. The only member of its genus, it has teeth that allow it to tear scales from other fishes. It will relentlessly attack silver-coloured or shiny tankmates, even larger predators, so it is best kept as a large shoal in a species setup. Scaleless and non-reflective fish are generally left alone.

The common hatchetfish (Gasteropelecus sternicla) is a freshwater hatchetfish from South America, described from Suriname. Its distribution is questionable, with records from the middle Amazon, Venezuela, Guyana, French Guiana and the Río Paraguay basin. It spends almost all of its time at or just below the surface. The most frequently seen of the silver hatchetfishes, it is peaceful but nervous and shy.

Geophagus brachybranchus is a cichlid from the Nickerie and Courantyne drainages of Suriname, also reported from Guyana and Venezuela. Generally rare in the aquarium hobby, it appears to be one of the commoner species in Australia, where it is often called the 'black-throated eartheater'. The largest wild specimen recorded measured 138 mm, but it is known to reach 180 to 200 mm in captivity.

Hoplisoma griseum, long known as Corydoras griseus, is an armoured catfish from Guyana, where it may be restricted to the Potaro River in the Essequibo watershed. It was described from aquarium specimens said to come from 'very small water courses of the Amazon', and the type locality was later corrected to the Potaro by Nijssen and Isbrücker (1980). Similar-looking fishes from Rondônia state, Brazil, carry the 'C' numbers C040 and C073, and C134 from Amapá state is also comparable.

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.

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.

The threespot leporinus, Leporinus friderici, is an anostomid from much of the Amazon system, with further records from the Guianas and Trinidad. It grows to 350 to 400 mm and needs an aquarium with base dimensions of at least 240 by 90 cm. Across this enormous range the fish differ in morphology and, especially, colour pattern.

The elongate mouse catfish, Leptodoras linnelli, is a doradid catfish from river drainages of northern South America in Venezuela, Guyana and Brazil. It is found over sandy substrates in deeper, flowing sections of rivers and prefers cooler water than many related species. Totally unaggressive and schooling in nature, it is seldom exported and usually turns up only as bycatch among shipments of Opsodoras leporhinus or Hassar orestis.

The red-finned pike cichlid, Lugubria johanna, is a large pike cichlid that ranges over much of northern South America. It is known from the Orinoco, Essequibo, Oyapock and Approuague basins among others, mostly in faster moving rivers and streams, and a number of colour forms have developed across its range. Growing to 30 cm, it can be aggressive, especially towards its own kind, and will eat any fish small enough to be considered food.

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 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 twostripe pencilfish, Nannostomus digrammus, is a lebiasinid from the central Amazon basin in Brazil and the Rupununi basin in Guyana. Rare in the hobby, it usually arrives as bycatch among shipments of other fishes. It is most similar to N. bifasciatus but has an adipose-fin, and its small size and timid nature make it a poor community fish.

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 barred pencilfish, Nannostomus espei, is a lebiasinid considered endemic to the Mazaruni River system in Guyana. The only member of the genus to show a vertically-barred pattern permanently, it has five dark bar-like markings on each flank where congeners have horizontal stripes. It inhabits sluggish blackwater habitats where pH can be as low as 4.0, and its small size and timid nature suit a tank of its own or diminutive tankmates.

The blackstripe pencilfish, Nannostomus harrisoni, is a lebiasinid that appears endemic to the Demerara River basin in eastern Guyana. Quite rare in the hobby, it is more often exported as bycatch among shipments of N. eques than in numbers. It inhabits sluggish tributaries, swamps and flooded forest, and mature males show red in the pelvic, anal and caudal fins.

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 least pencilfish, Nannostomus minimus, is a tiny lebiasinid from the Potaro and Mazaruni systems of the Essequibo basin in Guyana. The second-smallest member of the genus after N. anduzei, it is poorly known in the hobby and has been exported under the name N. marilynae. In the Mazaruni it occurs with N. espei in sluggish blackwater habitats but tends to keep to marginal zones with abundant cover.

The three-lined pencilfish, Nannostomus trifasciatus, is a lebiasinid widespread in the western Amazon basin in Brazil, Peru, Colombia and Bolivia. Fairly ubiquitous in the trade, it is less demanding than many congeners and a good choice for a newcomer to pencilfishes. Many fish on sale are farmed, and wild populations vary in colour pattern, one being marketed as 'super red' for its unusually long red stripe.

The one-lined pencilfish, Nannostomus unifasciatus, occurs in the upper Amazon and upper Orinoco basins in Brazil, Bolivia, Colombia and Venezuela. A popular aquarium fish, it swims at an oblique angle, a trait shared only with N. eques. It differs from that species in lacking dark brown spots on the body scales and normally having an ocellus in the upper caudal-fin lobe.

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 roman nose angelfish, Pterophyllum leopoldi, is a cichlid from the lower Rio Negro in Brazil and the Rupununi and Essequibo basins of Guyana. It can be told from other members of the genus by up to 11 vertical stripes, a dark patch over the operculum and the roman nose that gives it its name. Reportedly one of the more aggressive species in the genus towards conspecifics, it should be kept in a group of four or more to prevent bullying.

The red bellied piranha, Pygocentrus nattereri, occurs through much of the Amazon basin and south into the Paraná and Uruguay river systems. Famed as a rapacious predator, it is among the most notorious freshwater fishes in the world. According to Herbert Axelrod (1976), the myth began with a feeding frenzy staged for Theodore Roosevelt in Brazil in 1913. Usually only juveniles form aggregations, and the species is relatively easy to breed in the aquarium.

The whitespot eartheater, Satanoperca leucosticta, is a cichlid from the Guiana Shield in Guyana, Suriname, eastern Venezuela and northern Brazil. Farmed in several countries, it is frequently available in the ornamental trade. It is often confused with S. jurupari but is easily recognised by the prominent white spots or vermiform markings on the sides of the head. A larvophilous maternal mouthbrooder, it has been bred in aquaria.

The white-spotted pike cichlid, Saxatilia albopunctata, is a pike cichlid from Guyana, Suriname and French Guiana. Its range runs from the Demerara to the Approuague, in slow-moving forest streams, tributaries and pools over sandy substrates, dimly lit by overhanging vegetation. An aggressive species, it can be kept with other large cichlids or on its own, and it grows to about 20 cm, though usually no more than 15 cm in aquaria.

The threadfin acara, Acarichthys heckelii, is a cichlid from the northern Amazon basin in Colombia, Peru and Brazil and the Essequibo in Guyana. The only member of its genus, it grows to around 200 mm and digs incessantly, and it is susceptible to deteriorating water quality. Some adults show sudden, extreme aggression towards conspecifics that can kill weaker fish, and the problem decreases as tank and group size increase.

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.

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 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.

The peacock bass, Cichla ocellaris, is a large predatory cichlid native to Colombia, Venezuela, Guyana, Suriname, French Guiana and Brazil. Introduced populations exist in several countries, including Singapore and the USA. Often sold as small juveniles, it grows to around 75 cm and needs a tank of at least 10 x 3 x 4 feet as an adult, and it will eat any tankmate small enough to be considered food.

The speckled pavon, Cichla temensis, is a large peacock bass from the Rio Negro, Uatumã and Orinoco basins in Colombia, Venezuela, Guyana and Brazil. One of the largest Cichla species at up to 99 cm, it is more suited to public aquaria and needs a tank of at least 10 x 3 x 4 feet as an adult. Often sold as small juveniles, it is also fished as a sport fish.

The grass carp, Ctenopharyngodon idella, is a large cyprinid native to the Amur River system in eastern Russia and northeastern China. Adults typically reach 800 to 1200 mm, making it a wholly unsuitable aquarium subject, though an albino form is traded. Widely introduced for aquaculture and weed control, it has caused serious damage to natural waters, and unwanted fish should never be released.

The blackstripe cory, Hoplisoma bondi, long known as Corydoras bondi, is an armoured catfish from Venezuela, Guyana and Suriname, including the Essequibo and Courantyne systems. It was once considered common in the hobby, but many fish traded under the name may be the similar H. sipaliwini or H. coppenamense. H. sipaliwini has larger body spots and a dark marking on the first dorsal-fin rays, while H. coppenamense is more orangish.

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.

The silver arowana, Osteoglossum bicirrhosum, is a large predator from the Amazon basin, plus river systems in Guyana and French Guiana. Reaching 80 cm, it is largely unsuitable for the home aquarium, and although juveniles are readily available, few private aquarists can house an adult long-term. Juveniles have a single dark lateral stripe, while in those of its only congener, O. ferreirai, most of the body and fins are dark.

The ripsaw catfish, Oxydoras niger, is a large doradid catfish from many of the major river systems of northern South America. Reaching 90 cm, it is only for the experienced fishkeeper and best suited to public aquaria. Much more peaceful than its common name suggests, it takes that name from the spines along the lateral line. It was previously referred to Pseudodoras niger.

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.

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.