Taxonomy & naming
Australoheros tembe was first described in 1995 by the Argentine ichthyologists Jorge R. Casciotta, Stella M. Gómez and Nora I. Toresanni, who placed it in the catch-all genus Cichlasoma and titled their paper, with deliberate quotation marks, "'Cichlasoma' tembe, a new cichlid species from the río Paraná, Argentina" (Ichthyological Exploration of Freshwaters 6(3): 193-200). The quotation marks flagged what was already obvious to specialists: the sprawling genus Cichlasoma was a taxonomic holding pen that would eventually be broken apart. The holotype, an adult from the Arroyo Urugua-í above the Salto del Urugua-í waterfall, is housed at the Museo de La Plata under register MLP 9059. In 2006 Oldřich Říčan and Sven O. Kullander erected the genus Australoheros for the South American chanchitas and transferred this species into it; their 2008 revision of the genus in the Uruguay and Paraná drainages (Zootaxa 1724) formally treated it as Australoheros tembe and placed it in the forquilha species group, alongside the very similar Australoheros forquilha. The combination users sometimes attribute to a single 2008 paper is therefore better understood as a description by Casciotta, Gómez & Toresanni in 1995 and a generic reassignment by Říčan & Kullander in 2006. Within the family it sits in the heroine cichlids (tribe Heroini; the Cichlid Room Companion catalogues it under the older tribe name Therapsini). The species epithet 'tembe' is a Guaraní word meaning lips, chosen for the fish's enlarged fleshy lip folds — not, as is sometimes assumed, after a river of that name.
Morphology
This is a modestly sized cichlid: the largest measured specimen is about 5.5 in in standard length (snout to tail base), and most fish seen are smaller. The body is deep and laterally compressed in the typical chanchita mold, with a fin count of fifteen to seventeen dorsal spines over eight to ten soft rays, and five to six anal spines over seven to nine soft rays. Its single most distinctive feature is its color in life: wild-caught Australoheros tembe show a beautiful green ground color across the flanks, a tone not known from any other Australoheros and one that, frustratingly for aquarists, the fish stops producing under aquarium conditions. Like all members of the genus it can throw up a series of dark vertical bars when stressed, courting or guarding young. The fleshy, thickened lips that give the species its name are a useful field mark separating it from look-alike congeners. Sexual dimorphism is most evident in breeding dress rather than in everyday appearance: when spawning, both sexes take on a yellowish-to-whitish ground color crossed by bold black bars, but females develop a blackened belly and lower head, while males instead flush pinkish across the same region — a pattern reminiscent of the related Australoheros minuano. Notably, Australoheros tembe is the one species in the genus that barely expresses the Australoheros signature breeding marking of broken, interrupted bars along the back, which makes its breeding pattern look cleaner than that of its relatives.
Habitat
Australoheros tembe is, as far as the published record shows, endemic to the Arroyo Urugua-í, a tributary stream of the río Paraná in Misiones, Argentina — the narrow, subtropical-rainforest wedge of land between the Paraná and Uruguay rivers. The describing authors later (Casciotta et al. 2003) noted a single specimen identified as Australoheros cf. tembe from the Arroyo Fortaleza in the adjacent río Uruguay drainage, but Říčan and Kullander cautioned that this individual could equally be the closely allied Australoheros forquilha, which is confirmed from río Uruguay tributaries nearby; the species' presence in the Uruguay basin is therefore unconfirmed rather than established. The Urugua-í itself is a moderately fast-flowing forest stream running over a mixed bottom of mud, sand, sand-with-gravel and exposed bedrock. Adults are taken in the quieter pockets of the channel, in water roughly 2–3 ft deep over rock or sand, while juveniles keep to shallower margins of about 1 ft with sandy bottoms and aquatic plants. No detailed in-situ chemistry has been published for this species; the Misiones rainforest streams it inhabits are typically warm, soft, and slightly acidic to near-neutral, and the temperature and pH figures given here are taken from that habitat type and from the well-documented tolerances of its congeners rather than from measurements on Australoheros tembe itself — a gap worth flagging honestly.
Feeding
No dedicated diet study has been published for Australoheros tembe, and FishBase carries only a model-derived trophic level of about 3.2, placing it among the generalist invertebrate-leaning omnivores rather than the dedicated predators or herbivores. That estimate fits the genus well: chanchitas are opportunistic substrate-oriented foragers that take aquatic insect larvae and other small invertebrates, worms, crustaceans, and plant and detrital material from the stream bed, picking and sifting among sand, gravel and leaf litter. The species' thick, fleshy lips — the feature its name commemorates — are the kind of structure often associated in cichlids with working over rocky and crevice-rich surfaces, though no feeding mechanics have been documented for this fish specifically. In the community of a Misiones forest stream it would function as a mid-level benthic forager rather than a top predator.
Mating
Australoheros are biparental substrate spawners that form pairs and defend a territory together, and Australoheros tembe follows this template. Detailed pair-formation behavior has not been described from the wild, but the genus is characteristically territorial around the nest site, with the bonded pair driving other fish away from a defended patch of substrate. The clearest behavioral observations for this species come from aquarium spawnings reported by Casciotta and colleagues (2003): pairs adopt the breeding livery described above — barred, with the female's belly and lower head turning black and the male's flushing pink — and both partners take an active role through the spawning and brood-guarding cycle. As in other chanchitas, courtship and spawning are tied to the pair establishing and holding a small territory centered on a cleaned spawning surface.
Breeding
Like its congeners, Australoheros tembe is an open or sheltered substrate spawner rather than a mouthbrooder: the female deposits adhesive eggs on a cleaned hard surface such as a stone or submerged wood, and the pair tends them together. The aquarium account by Casciotta et al. (2003) records that both sexes guard the eggs and then the free-swimming fry, and that once the young are mobile the male develops the same black belly-and-head coloration the female showed earlier — a shift in his signaling as the pair settles into joint brood care. Clutch size has not been reported for this species; congeneric Australoheros typically produce broods on the order of a few hundred eggs, which is the best available guide and is flagged here as a genus-typical figure rather than a measured one for Australoheros tembe. Parental care is biparental and extended through the free-swimming stage, consistent with the rest of the genus; no specific data exist on egg or larval development times for this fish. There is no documented commercial aquarium trade in true Australoheros tembe — it is a narrow-range endemic rarely if ever exported — so almost everything known about its reproduction comes from that handful of captive observations and from inference across the genus.
In the aquarium
Australoheros tembe is genuinely rare in the hobby — it has almost never been exported commercially, and any fish sold under that name should be viewed with skepticism unless the seller can trace the stock to a documented wild collection from the Arroyo Urugua-í or to a hobbyist lineage derived from one. In practice, care for the species is extrapolated almost entirely from the broader chanchita complex (Australoheros facetus, Australoheros forquilha, Australoheros minuano and their kin), and keepers should treat any account of Australoheros tembe specifically as genus-typical guidance, not species-verified data — which is what it is.
A tank of 30 US gal (roughly 39.5 in) is the minimum worth considering for a pair, and something larger is preferable once the pair begins defending a territory and herding fry: chanchitas are not passive fish around spawning time. The substrate should be sand or fine gravel — the species is a benthic forager that appreciates being able to pick and sift — with flat stones, rounded cobbles, or a piece of driftwood providing candidate spawning surfaces. Dense plantings can soften the tank and reduce aggression but be aware that the fish may excavate the substrate near a chosen spawning site; potted or robust-rooted plants do better than loosely planted stem plants at this stage. A tight-fitting lid is useful, as with most active cichlids.
Water chemistry is relatively forgiving within the soft-to-neutral range: target 64–79 °F, pH 6.0–7.5, and moderately soft to medium-hard water. The temperature range is one of the most practically important features of this fish — as a Misiones highland stream dweller it tolerates genuinely cool conditions, and there is no need to heat its tank to tropical temperatures in a temperate climate. At the lower end of the range it remains active and healthy; running it warm and soft is neither necessary nor advisable. Strong filtration with gentle flow is more useful than powerful turnover that creates open-water turbulence.
Compatibility outside the breeding pair is the main management challenge. Chanchitas are moderately aggressive, especially when holding territory, and Australoheros tembe is not a candidate for a busy community tank of small tetras or similarly sized Neotropical dwarfs. Suitable tankmates in a species-focused or biotope-appropriate setup are similarly robust fish from the upper Paraná and Misiones region — larger characins (Salminus, Brycon relatives at a size that cannot be eaten), loricariid catfishes, and similar substrate-oriented cichlids of comparable size where space allows. Single-species maintenance of a bonded pair is the simplest arrangement. Two males in the same tank without sufficient space will fight, and a male that has decided a female is not his partner will harass her persistently; it is worth having a divider available.
The main mistakes keepers make with chanchitas generally are keeping them too warm, pairing them in tanks too small to allow the female an escape route if the male turns hostile, and underestimating how vigorously they defend fry. Breeding, if a compatible pair forms, follows the open substrate-spawner pattern: the pair cleans a flat stone or other hard surface, the female lays adhesive eggs in rows, and both parents take turns fanning and guarding the clutch. Once the fry are free-swimming the parents continue to shepherd them as a mobile school, and the male may take on the brooding coloration previously seen in the female. At this stage the pair should be considered capable of injuring anything that enters their defended zone, including the keeper's hand. Fry accept freshly hatched brine shrimp nauplii and microworms readily. Raising a cohort to juvenile size is straightforward as long as water quality is maintained.
Conservation
The IUCN Red List assessed Australoheros tembe as Near Threatened in 2020 (assessed 1 November 2020 by C. Baigún, F. Brancolini and P. Minotti; published 2020), under criterion B1a — the category that flags a species with a very small geographic range. That is the crux of its situation: a fish confidently known from a single small stream system has, by definition, a restricted extent of occurrence and no buffer if that one drainage is degraded. The Arroyo Urugua-í has already been heavily modified, most consequentially by the large Urugua-í hydroelectric dam completed in 1989, which drowned the historic Salto del Urugua-í waterfall and converted a long reach of free-flowing stream into reservoir. Dams of this kind fragment fish populations, alter flow and temperature regimes, and replace running-water habitat with still water — pressures that bear directly on a current-loving stream endemic. The wider Upper Paraná and Misiones region faces the familiar combination of hydropower development, deforestation of the Atlantic Forest, agricultural runoff and the spread of introduced fishes, all of which compound the risk to a species with nowhere else to go. The fish has no CITES listing and no fishery interest; its vulnerability is geographic, not from harvest. Because the green-colored, single-stream Australoheros tembe is so easily confused with Australoheros forquilha and other chanchitas, even basic monitoring of its true range and status is harder than it should be — a reminder that for narrow-range Neotropical endemics, taxonomic clarity and conservation are the same problem.