Parana basin

Abramites spp. are separated from other anostomids primarily on the basis of their relatively deeper bodies and presence of a prominent, post-pelvic median keel, a feature unique to the genus. At time of writing A. eques is the only other species recognised and is native to the Río Magdalena drainage in western Colombia. It can be distinguished by possession of 13-14 bra...

An obligate piscivore capable of consuming surprisingly surprisingly large prey. Newly-imported specimens may refuse to accept anything but live fishes although most can be weaned onto dead alternatives once they recognise them as edible, and some even learn to accept dried foods- Like the vast majority of predatory fishes this specie...

The genus Ageneiosus was at one point classified in the family Ageneiosidae alongside the genus Tetranematichthys, but this was not accepted by all authors. The grouping remains poorly-studied with the last major revision having been conducted by Watson (1990) in his unpublished dissertation, in which A. inermis was included under the currently synonymous name A. brevifilis. It can be separated from the majority of the genus (except A. marmoratus) by possession of a truncate caudal fin, and from...

Apparently this species is polymorphic with body patterning varying significantly depending on locality. Individuals collected from black water habitats tend to be noticeably darker in overall colouration, for example, with this being particularly evident among populations from the Guiana Shield. The genus Ageneiosus was at one point classified in...

This species is sometimes confused with unidentified fishes such as A. sp. 'L352'. It can be told apart from closely-related congeners by possession of relatively long maxillary barbels which are free from the lower lip, and a colour pattern consisting of small spots on the head and vermiform lines on the body in males, and small spots all over the head and body in females.

A good beginner's tetra, as it's a hardy species that will adapt to a relatively wide range of conditions. In a well-insulated house it can even be kept in an unheated tank, although it won't be as colourful as when kept in warmer water. It's also quite long-lived and captive specimens over ten years old are not unheard of...

This species is normally referred to as A. paraguayensis, but that name has been considered a synonym of A. nattereri since 2003. Confusion remains however, as the type locality for the latter is 'Villa Bella', now known as Parintins, a settlement on the main Amazon river channel between Manaus and Santarém and many kilometres away from the majority of confirmed localities.

Endemic to the Paraguay, Paraná and Uruguay river drainages in Brazil, Paraguay, Argentina and Uruguay. The smallest of the three Aphyocharax species seen in the hobby, the redflank is relatively uncommon in the hobby in the aquarium trade. It is also known as the Green Fire Tetra.

Numerous ornamental forms of this species have been selectively-bred for the aquarium trade. It has also been assigned the 'A' number A234 under the DATZ system with possibly conspecific, related forms similarly numbered A103, A104, and A105 depending on locality.

Apistogramma commbrae and other members of the commbrae complex can be distinguished from congeners by the conspicuous double caudal peduncle spot. This species may also be polymorphic, with some males exhibiting red and blue markings on the cheeks and a yellow gular region.

This species is assigned the 'A' number A204 under the DATZ system with possibly conspecific, related forms coded A205 or A206 depending on collection locality and representing populations from Argentina and the rio Guaporé, respectively. The genus Apistogramma is among the most speciose of South American cichlid genera with around 70 species valid at present but many more awaiting description.

A. taurus can be told apart from congeners by the following combination of characters: infraorbitals and preopercle covered by thick skin and not visible externally (vs. covered by thin skin and externally visible in other Aspidoras); nuchal plate reduced, covered by thick skin and not visible externally (vs. well developed, covered by thin skin and visible externally); lateral line absent posterior to two small lateral line ossicles (vs. lateral line present on at least first body plate).

Despite the ubiquity of its name in aquarium literature, confusion surrounds its true identity. Given it's the only member of the genus occurring on the island, fish from Trinidad do presumably represent C. aeneus (see our image), but the classification of those from other localities appears far from certain. Today the species is accepted to occur throughout much of South America, and indeed similarly-patterned fish do occur across a large portion of the continent. Some of these, such as the gree...

Brochis was first synonymised with Corydoras by Britto (2003), since the latter genus cannot be considered monophyletic if the former is accepted as valid. This decision has been supported in subsequent phylogenetic studies by Shimabukuro-Dias et al. (2004) and Alexandrou et al. (2011), although the name Brochis is still common in aquarium literature. It is likely that the genus will be revalidated and expanded in the future following a required taxonomic review of the subfamily Corydoradinae as suggested by Alexandrou and Taylor (2011).

The Río Calchaquí rises at almost 6000 m AMSL and flows swiftly through a mountainous valley where it is largely fed by snow melt. The climate is semi-arid and cool with an air temperature of 12-18°C, while rainfall is largely concentrated during summer when the flow can be torrential. The water is hard and rich in salts, with pH measured at 8.04 during the month of August. Aquatic vegetation and filamentous algae grow around the margins and in tributaries.

It exhibits slightly different behaviour to the majority of congeners in that it tends to swim in midwater and spends a large proportion of its time away from the substrate. Its morphology exhibits corresponding adaptations towards a pelagic existence with a relatively large eye, a more terminal mouth position, more strongly-forked caudal-fin, and more symmetrical body shape than most other Corydoras species.

It also exhibits morphological adaptations to an existence among rocks in a flowing environment, such as a cryptic colour pattern, reduced spine length in the dorsal and pectoral fins, ventrally-oriented pectoral fins, slightly emarginate caudal-fin, and reduced body depth. Reduced fin spines and body depth are typical features associated with the related genus Aspidoras, but the...

This species is also known as the 'pearlscale' or 'mother-of-pearl' cichlid in deference to the iridescent body scaling. It's also worth noting that fishes sold as Gymnogeophagus australis in Europe are 'G.' brasiliens is more often than not. Wild specimens exhibits significant dissimilarities in body colour and patterning depending on locality with basic colouration being dominated by varying shades of blue, green or yellow, for example. Some populations al...

Widely-distributed throughout much of the Paraná and Uruguay river systems in Brazil, Paraguay, Argentina and Uruguay. Some records from Buenos Aires province, Argentina are now considered to refer to the congener H. togoi (Miquelarena and López, 2006) so the common vernacular name 'Buenos Aires tetra' may not...

This species is very common in the aquarium trade and is also referred to as 'jewel', 'red minor', 'blood', or 'callistus' tetra. A number of selectively-bred ornamental strains have been developed, including 'metallic', 'long-finned', 'balloon' and 'fairy-fin'. Characiformes is among the most diverse orders of freshwa...

Its native rivers flow through one of the most densely-populated and industrialised parts of Brazil, and have suffered greatly from dam construction, water abstraction, pollution, introduced species (including over 40 exotic freshwater fishes in the rio Paraíba do Sul alone), and other forms of anthropogenic degradation. H. flammeus is now uncommon or even extinct across much of its putative natural range, and in Rio de Janeiro state only a handful of highly-fragmented populations remain at best, with the mo...

This species has been a ubiquitous aquarium fish since its discovery, and is produced on a commercial basis in several countries, therefore wild fish are no longer collected. An ornamental albino form is sometimes available. Apart from its distinctive colour pattern, it can be identified from related species via the following combination of charac...

The majority of records pertain to the rio Guaporé (Río Iténez in Bolivia), the main affluent of the rio Mamoré, which drains the vast tropical wetland known as the Pantanal, and the upper rio Paraguai, which also has its headwaters in the Pantanal but flows in the opposite direction. The Guaporé and Paraguai are connected due to rising water levels during the annual wet season.

Type locality is given simply as 'Amazon River, Brazil' and according to current thinking this species has a huge natural range encompassing the Amazon River system in Brazil and Peru plus the Paraná-Paraguay drainage in southern Brazil and Paraguay and rio São Francisco basin in southern Brazil. Specimens in our images were collected fro...

Metynnis maculatus

This species has been traded as 'six-eyed tetra' in reference to its colour pattern comprising two dark spots on each flank plus the eye. Based on the extensive review of the genus by Lucena and Malabarba (2010), in which nine new species were described, P. tegatus can be told apart from congeners by the following combination of characters: lateral line incomplete with 8-13 perforated scales; laterally elongate humera...

A paternal 'lip brooder' which has been bred in aquaria. Post-spawning the male carries the eggs attached to his labial barbels for a period of 12-14 days after which the fry hatch with a large yolk sac attached, this being absorbed over the next 48 hours or so. During incubation the behaviour of the male i...

Famed as a rapacious predator capable of rapidly stripping flesh from bone and a danger to any animal entering its native waters, P. nattereri is among the most notorious freshwater fishes in the world. As a result, displays featuring this “bloodthirsty” creature are found in most public aquaria, grisly Hollywood movies have been released, and the species has become popular in the aquarium trade. Little of this infamy is based on factual evidence, however.

S. pappaterra is relatively rare in the ornamental trade and much sought after by enthusiasts. It is easily distinguished from all known congeners by presence of a series of prominent black blotches beneath the dorsal-fin, plus a well-defined dark band extending along the side of the body. In recent genetic analyses its genetic distinctness was strongly supported, with S. jurupari and S. leucosticta its closest relatives.

Scleromystax spp. are foraging omnivores, and most will accept sinking dried foods as well as small live and frozen varieties such as chironomid larvae (bloodworm), Tubifex, etc. Feeding a varied diet will ensure the fish are in optimum condition. Under no circumstances should they be expected to survive on 'left-overs' from other inhabitants of the aquarium or relied on to 'clean' the aquarium.

Known from minor rivers in the coastal states of São Paolo, Paraná, and Santa Catarina, southern Brazil, plus some tributaries of the rio Paraná basin in Paraguay. Type locality is 'Paranaguá, 25°32'S, 48°36'W, Paraná, Brazil'.

A number of sources state that S. brandtii can be identified by the relatively anterior position of the anal-fin origin beneath the first few dorsal-fin rays. However, images of specimens collected from the rio São Francisco, where it is the only member of the genus present, suggest that this is not always the case and this is also supported by the figure from Eigenmann (1915). No recent diagnosis of the species is available.

T. stellatus is superficially similar to its only congener T. securis, but can immediately be identified by the presence (vs. absence) of a prominent dark spot in the dorsal-fin. It is sometimes traded as 'platinum hatchetfish'. The genus Thoracocharax was originally erected by Fowler in 1906 as a subgenus of Gasteropelecus, but was elevated to generic status by Weitzman (1960).

C. aurofrenatus is currently understood to occur throughout much of the Río Paraguay-Paraná system in Paraguay, and has also been recorded in Argentina and Bolivia. It was described from Paraguay with type locality given as 'Aguada near Arroyo Trementina'. The latter is stated to be a tributary of the 'Rio Aquido Canigi'.

This species is not available on a commercial basis but was collected and introduced to the aquarium hobby by Hans Georg-Evers in 2010. It's similar in appearance to a number of congeners including C. diphyes, C. erhardti, C. garbei, C. paleatus and C. steindachneri but can be told apart from most of them by possession of two large, indistinct, dark blotches in the middle of each flank.

Known from southern Sao Paulo to northern Santa Catarina states in eastern Brazil, including the rios Jaraguá, Iguaçu, Tejuco, Ribeira de Iguape, Guabiroba, Tibagi, Capivari, Lindo, Itapocu, São Pedro, and upper Rio Paranapanema.

This species is exceptionally rare in the aquarium hobby. Among congeners it is most similar to C. lacrimostigmata but can be distinguished by...

Known only from the rio Ivaí basin, a tributary of the rio Paraná in Paraná state, southern Brazil. Type locality is 'Brazil, Paraná, Cândido de Abreu, rio Maria Flora, tributary to rio Ubazinho, rio Ivaí basin...

Generally peaceful making it an ideal resident of the well-researched community aquarium. It is perhaps best-maintained alongside similarly-sized characids, gasteropelecids, lebiasinids, smaller callichthyid or loricariid catfishes and non-predatory, medium-sized cichlids. Try to buy a mixed-sex group of at least 8-10 specimens, incl...

Wild fish are probably foragers feeding on algae, organic detritus, small insects, worms, crustaceans, and other zooplankton. In the aquarium it's easily-fed but the best condition and colours offer regular meals of small live and frozen foods such as bloodworm, Daphnia, and Artemia, alongside good quality dried flakes and granules, at least some of which should include additional plant or algal content.

This species was formerly considered to be represented by the L-numbers L113 and L234 but it appears that only the former is native to the Paraná, Paraguay and Uruguay drainages, whereas L234 is collected in the rio São Francisco in eastern Brazil. M. barrae and M. sp. 'LDA097' are also exported from the São Francisco system.

L234 was previously applied to M. paranus, which has also has the L-number L113 assigned to it. However M. paranus is native to the Paraná, Paraguay and Uruguay drainages, whereas L234 is collected in the rio São Francisco so appears to represent an unidentified species. M. barrae and M. sp. 'LDA097' are also exported from the São Francisco system.

Occurs naturally in Brazil, Paraguay, Uruguay and Argentina with feral populations in Australia, New Zealand, Ethiopia and Malawi which were purportedly introduced for purposes of mosquito control but are now considered invasive. Following Lucinda (2008) its natural range comprises the Lagoa dos Patos system, lower rio Uruguai, rio Tramandaí, and rio Mampituba in Rio Grande do Sul st...

Following Fink (1993), P. piraya can be distinguished from congeners by the following combination of characters: adipose fin with rays in larger specimens (vs. always without rays in other Pygocentrus species); branched dorsal-fin rays 15-18, usually 16 (vs. 14-18, usually 15); usually 7 neural spines anterior to first pterygiophore (vs. usually 6); vertebrae 36-39, usually 38 (vs. 35-38, usually 36). It can also be identified by colour pattern since it possesses distinctive bright yellow-orange pigmentation on the lower jaw, opercle and lateral body in life.

R. vulpinus is the most widely-distributed member of the family Cynodontidae. Type locality is given simply as 'Brazilian rivers', but this species is currently understood to be distributed in the Amazon basin from the Río Ucayali system in Peru, eastward as far as the rio Xingu in Brazil, plus the rio Tocantins and Rio Capim basins. It's also known from the Río Orinoco ba...

Scleromystax spp. are foraging omnivores, and most will accept sinking dried foods as well as small live and frozen varieties such as chironomid larvae (bloodworm), Tubifex, etc. Feeding a varied diet will ensure the fish are in optimum condition. Under no circumstances should they be expected to survive on 'left-overs' from other inhabitants of the aquarium or relied on to 'clean' the aquarium.

The two ponds where H. auca was collected were located on a sand bar deposited by the nearby Paraná river during the Pleistocene. At time of collection the substrates were composed of sand with submerged vegetation dominated by Egeria najas plus floating Eichhornia in marginal areas.

Known only from headwaters of the upper Paraná river basin in the Federal District plus the neighbouring state of Goiás, central Brazil. Type locality is 'Planaltina, Lagoa Fervedeira, Goiás, Brazil' with additional records existing mostly from the rio São Bartolomeu including the Bananal, Santa Maria-Torto and Gama tributary systems.