Taxonomy & naming
Odontostilbe weitzmani was described by J. C. Chuctaya, C. Bührnheim, and L. R. Malabarba in 2018, with the holotype — MZUSP 121648, a specimen of 1.5 in standard length — collected from a tributary of the upper rio Paraná near Itirapina, in the state of São Paulo, Brazil. The species belongs to Odontostilbe, a genus in the subfamily Cheirodontinae (family Characidae) that is distinguished from allied genera by the presence of mesopterygoid teeth and other osteological and soft-tissue characters. The terminal mouth and a distinctively high number of olfactory rosette lamellae (20–21) are among the characters that separate O. weitzmani from its congeners.
The valid name is governed by the Catalog of Fishes (Eschmeyer, Fricke & van der Laan), which lists Odontostilbe weitzmani Chuctaya, Bührnheim & Malabarba, 2018 as the accepted combination. Because the species was described within Odontostilbe and has not been moved, no parenthetical authority is required. The description was published in the journal Neotropical Ichthyology, the principal venue for fish systematics in the region.
Morphology
Odontostilbe weitzmani is a slender, silvery cheirodontine tetra with a size range of 1–2 in standard length across measured specimens, making it one of the larger members of the genus. The body form is typical of the group: fusiform, moderately compressed laterally, with a small terminal mouth oriented roughly horizontally. Key diagnostic characters reported in the original description include the presence of mesopterygoid teeth — teeth on an internal element of the upper jaw that are absent or reduced in related genera — and a olfactory rosette bearing 20 to 21 lamellae, a count that helps separate this species from congeners.
Sexual dimorphism is present and takes the form characteristic of Cheirodontinae: males bear modified fin rays (likely hooks on the anal fin, a feature widespread in male cheirodontines and related tetras) and possess a gill gland — a patch of secretory tissue associated with the gill arch that plays a role in spawning behaviour. These male-specific structures are absent or reduced in females. Specific colouration data are not detailed in available sources beyond the general silvery-translucent appearance expected of small characids from clear Paraná tributaries.
Habitat
Odontostilbe weitzmani occupies stream tributaries of the upper Paraná basin in Brazil, a river network that drains much of the Brazilian Plateau before converging in the Paraná River proper. Confirmed rivers and drainage systems within the range include the rio Tietê, rio Piracicaba, rio Mogi Guaçu, and rio Corumbá — all tributaries of the upper Paraná system flowing through the states of São Paulo, Minas Gerais, Goiás, and Mato Grosso do Sul. The type locality is a stream near Itirapina, in the interior of São Paulo state.
The original description notes that portions of the species' range have been affected by hydroelectric dam construction, a widespread pressure throughout the upper Paraná basin since the mid-twentieth century. The region is largely cerrado savanna transitioning to agricultural land; the streams themselves are generally clear-water with sandy or rocky substrates. No specific water chemistry measurements (temperature, pH, conductivity) are recorded in the scientific literature for the sites where this species was collected, though upper Paraná tributaries in this region tend toward neutral to slightly acidic, soft-to-moderately soft water.
Feeding
No detailed dietary study of Odontostilbe weitzmani has been published. By comparison with other Odontostilbe species and cheirodontine tetras more broadly, the species is expected to be a micropredator or omnivore feeding on small invertebrates — insect larvae, microcrustaceans, and zooplankton — together with algal material and fine detritus encountered along stream margins and in mid-water.
In aquarium conditions, similar small cheirodontine characids accept a wide range of prepared and live foods: high-quality micro-pellets or small flakes, live or frozen Daphnia, Cyclops, baby brine shrimp, and micro-worms. Given the small terminal mouth typical of the genus, particle size matters — foods should be appropriately fine to be taken comfortably. A varied diet including live or frozen invertebrates is likely to support better colour and breeding condition than prepared foods alone.
Mating
Odontostilbe weitzmani has not been studied in detail in a spawning context, but its reproductive biology almost certainly follows the open, egg-scattering pattern shared across Cheirodontinae. Males of the subfamily characteristically possess anal-fin hooks — modified fin rays thought to facilitate contact and clasping during spawning — and a gill gland that may produce chemical cues during courtship. These structures are present in male O. weitzmani and indicate a reproductive mode involving direct male–female contact during the spawning act rather than simple broadcast spawning.
As with allied genera such as Serrapinnus and Compsura, spawning is expected to take place among fine-leaved vegetation or submerged roots, with the male closely following or guiding the female through the spawning site. Adhesive eggs are deposited in small batches. No sustained parental behaviour is expected: once spawning is complete, the adults disperse and take no further interest in the eggs or larvae.
Breeding
No captive breeding account for Odontostilbe weitzmani has been published, and the species remains rare in the aquarium hobby. Based on the biology of the subfamily, breeding is expected to follow the general cheirodontine pattern: pairs or small groups spawn over fine-leaved plants or synthetic mops, depositing small adhesive eggs that cling to the spawning medium by fine filaments. Adults will eat their own eggs, so in a breeding attempt the spawning mop or plant should be removed to a separate container promptly after spawning is observed.
Incubation time is not recorded for this species but is likely in the range of 24–48 hours at typical tropical temperatures, with free-swimming fry appearing within a few days of hatching. First foods would need to be very fine — infusoria, commercial liquid fry food, or rotifers — before the fry are large enough to take newly hatched brine shrimp. Growth in cheirodontine tetras of this size class is generally moderate. As with most newly described Paraná basin characids, the species is effectively unknown in captivity and any keeper who successfully breeds it would be making a genuine contribution to husbandry knowledge.
In the aquarium
Odontostilbe weitzmani is not established in the aquarium hobby and is not commercially available as of its description. As a stream-dwelling cheirodontine tetra from the upper Paraná basin, it would be expected to thrive under conditions similar to those recommended for other small Brazilian characids: soft to moderately soft water, neutral to slightly acidic pH, temperatures in the low-to-mid 20s Celsius, and good water quality with regular water changes. A well-oxygenated, lightly planted tank with open swimming space and subdued lighting would reflect the clear-water stream habitats it occupies in the wild.
Its small size (under 2 in SL) makes it suitable for a mid-sized community of peaceful, similarly scaled species, though its relative rarity means pairing it with conspecifics in a species-focused setup would be more appropriate for anyone who does obtain specimens. Like all small characids, it would be best kept in a group to reduce individual stress and promote natural behaviour. Should it become available in the hobby, it would likely attract interest from characid enthusiasts and specialists in the upper Paraná fauna.
Conservation
Odontostilbe weitzmani is assessed as Least Concern (LC) on the IUCN Red List, a status consistent with its occurrence across multiple tributaries of the upper Paraná basin and its apparent abundance where it is found. The species was reported as abundant within its range at the time of its description, and its distribution across four Brazilian states — São Paulo, Minas Gerais, Goiás, and Mato Grosso do Sul — provides some buffer against localised declines.
Nevertheless, the upper Paraná basin is one of the most heavily modified river systems in South America. Hydroelectric dam construction — explicitly noted in the original description as affecting portions of this species' range — has fragmented many tributaries, altered flow regimes, and inundated riverine habitats throughout the region. Agricultural run-off, deforestation of riparian zones, and water extraction for irrigation are additional pressures affecting the cerrado streams where this and many other endemic small fish occur. The Least Concern listing reflects current population status rather than the absence of threat, and continued monitoring of the upper Paraná fish fauna remains important as infrastructure development in the region proceeds.