Argentina

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 The grouping remains poorly-studied with the last major revision having been conducted by Watson (1990) in his unpublished dissertation, in which A. inermis was included under the currently synonymous name A. brevifilis.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...

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...

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.

This species is also referred to as 'velvet cichlid', 'red oscar', 'tiger oscar', or 'marble cichlid'. It is a popular aquarium fish although its adult size and typical life-span of 10-20 years must be taken into account before purchase. Numerous ornamental strains are now available, and while care is more-or-less identical for all of them a degree of additional care must be taken with the 'long-finned' variety which is a little less competitive than other forms.

A. bimaculatus is not a popular aquarium fish but is available on occasion exception, most often as a contaminant among shipments of other species. It's identity is also in question to an extent with the name currently applied to what is considered to represent a species complex comprising at least four taxa.

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...

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...

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...

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.

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.

Despite being a wholly unsuitable aquarium subject, C. idella is often traded as such, with an albino form having been developed specifically for the ornamental market. Individuals which have outgrown their aquarium or pond should never be released into natural waters, either, since this species has proven capable of causing serious environmental damage under a wide range of climatic conditions.

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.

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...

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...

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.