Taxonomy & naming
Odontostilbe parecis was described by Luisa Fernanda Bührnheim and Luiz R. Malabarba in 2006. Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & van der Laan) recognises the valid name as Odontostilbe parecis Bührnheim & Malabarba, 2006, placed within the family Characidae. The type locality is in the Parecis region of Mato Grosso, Brazil — an elevated plateau that forms the headwater divide between southern Amazon tributaries and the upper Paraná–Paraguay basin.
The genus Odontostilbe belongs to the tribe Stevardiinae within Characidae, a diverse lineage of small Neotropical tetras with broad distribution across South America. The generic name combines the Greek odontos (tooth) with stilbe (brightness or glitter), alluding to the dentition and silvery body typical of the group. The specific epithet parecis refers directly to the Parecis plateau and to the indigenous Paresí people of that region in Mato Grosso state.
Morphology
Odontostilbe parecis is a small, slender characid of typical Odontostilbe build: a laterally compressed, elongate body with a pointed snout, a small terminal mouth bearing the multicuspidate teeth characteristic of the genus, and the standard characid complement of a dorsal fin, an adipose fin, and a forked caudal fin. The body is silvery, often with a diffuse lateral stripe or midlateral iridescence that catches light when the fish schools. Precise size data from primary sources are not available in the consulted literature, but the genus typically reaches 1–2 in standard length.
Sexual dimorphism, where documented in close congeners, is modest: females are deeper-bodied and fuller in the abdomen when ripe, while males may be slightly more slender. No bright colour differences between sexes are described for this species.
Habitat
The species is associated with the Parecis plateau of central Mato Grosso state, Brazil, a highland dissected by headwater streams feeding both the Amazon basin (via the Juruena, Arinos, and Tapajós rivers) and the Paraná–Paraguay system. Streams on the plateau tend to run clear to lightly stained over sandy or rocky substrates, shaded by gallery forest, with soft to moderately soft, mildly acidic water.
Beyond the type-locality region, detailed habitat data for O. parecis specifically are limited in the available literature. By analogy with congeners and with the general ecology of Stevardiinae in comparable environments, the species likely inhabits slow to moderate current over fine substrate and leaf litter, sheltering among submerged roots and marginal vegetation in small forest streams and stream margins.
Feeding
Odontostilbe species are generally regarded as opportunistic micro-predators and omnivores, taking small invertebrates — microcrustaceans, insect larvae, and emerging insects — alongside fine organic matter and algal films in the water column and near the substrate. The multicuspidate teeth of the genus are adapted for seizing small prey rather than for herbivory.
In the aquarium, O. parecis can be expected to accept quality micro-pellets and crushed flake, and to thrive on regular offerings of appropriately sized frozen and live foods such as Daphnia, micro-worm, and newly hatched brine shrimp. A varied diet supports condition and, in groups, encourages natural schooling behaviour.
Mating
No published behavioural account of mating in Odontostilbe parecis is available. Based on the biology of the genus and of Stevardiinae more broadly, the species is expected to follow the open-water egg-scattering pattern common to small characids: males court ripe females with fin displays and lateral showing, with no territory formation or pair bond.
In the aquarium, spawning is typically prompted by a water change or slight temperature fluctuation, with pairs or small groups becoming briefly active and driving through fine-leaved vegetation or over moss. Eggs are scattered in small numbers, often adhesive, and no further interaction between the sexes occurs after release.
Breeding
Odontostilbe parecis has not been widely documented as a captive breeding subject in the hobby literature consulted. The likely breeding pattern — consistent with genus and subfamily norms — is a scattered-egg spawner depositing adhesive eggs among fine-leaved plants, Java moss, or synthetic spawning mops, with incubation of several days at typical tropical temperatures and no parental care. Adults will readily consume eggs if not separated.
For hobbyists attempting to breed the species, a small, dimly lit breeding tank with soft, slightly acidic water, a clump of fine-leaved vegetation or a spawning mop, and a well-conditioned group containing both sexes offers the best chance of success. Fry are very small at hatching and require infusoria or commercial liquid fry food before graduating to nauplii.
In the aquarium
Odontostilbe parecis is a peaceful, schooling micro-tetra best kept in groups of eight or more. A tank of 10–15 US gal is adequate for a small school, provided water quality is maintained and the setup includes some planted areas or fine-leaved vegetation for security. Soft, warm water with a slightly acidic to neutral pH reflects the species' natural environment on the Parecis plateau.
Because hobbyist documentation is limited, husbandry details are extrapolated from congeners. Tankmates should be similarly peaceful and small — other small tetras, small rasboras, dwarf corydoras, and comparably sized nano-fish are appropriate. The species is not currently widespread in the trade, and sourcing may require specialist importers or breeders with access to South American micro-characids.
Conservation
Odontostilbe parecis has not been formally assessed by the IUCN Red List and carries no current conservation status. Its distribution appears tied to the Parecis plateau of Mato Grosso, a region where rapid expansion of soy and cattle farming has been a major driver of deforestation and stream degradation over recent decades. Headwater gallery forests — the typical habitat of small Stevardiine tetras — are among the most vulnerable ecosystems in this agricultural frontier.
While no specific data on population size or trend are available for this species, the combination of a restricted endemic range and continuing land-use pressure in its region of origin suggests that monitoring and formal assessment would be warranted. It is not known to be targeted by the ornamental fish trade.