Taxonomy & naming
Hemigrammus brevis was described by Mabel Gillmore Ellis in 1911. Ellis is the married name of Mabel Durbin, who described a substantial number of characiform species during the early twentieth century; she is credited under the name Ellis throughout formal taxonomic usage. The species is placed in Hemigrammus, a large genus of small characids in the family Characidae, distinguished by scaled caudal-fin lobes — a character that separates Hemigrammus from the otherwise similar Hyphessobrycon.
The specific epithet brevis is Latin for 'short', and the ETYFish Project notes the allusion likely refers to the short snout — shorter than half the eye diameter — and possibly to the short anal sheath, which covers the bases of the first nine anal-fin rays with around five scales. Catalog of Fishes (Eschmeyer, Fricke & van der Laan) records the valid name as Hemigrammus brevis Ellis, 1911.
Morphology
Hemigrammus brevis is a slender, moderately compressed tetra reaching a maximum total length of about 1.5 in. Like most members of the genus it has the standard characid plan: a single dorsal fin, an adipose fin, a forked caudal fin, and the diagnostic scaled caudal-fin lobes that define Hemigrammus. The body is silvery with the translucent quality typical of small stream tetras.
Little detailed morphological description is available in the hobbyist literature for this species; it is a relatively plain fish compared with the more popular aquarium Hemigrammus. The short snout — which gave rise to its name — is a distinguishing meristic feature noted in the original description. Sexual dimorphism is subtle at this size range, with females potentially showing a rounder abdomen when gravid, as is typical across the genus.
Habitat
Hemigrammus brevis is distributed in the São Francisco River basin of Brazil. The São Francisco is one of the great river systems of eastern South America, draining a large area of the Brazilian interior before reaching the Atlantic in the northeastern region. FishBase characterises the species as freshwater and benthopelagic, and assigns it to subtropical thermal conditions consistent with the São Francisco's mid-elevation drainage.
Within this basin the species occupies the freshwater habitats typical of small Hemigrammus: shallow, vegetated stretches of river margin and backwater, where dense riparian cover and submerged macrophytes provide shelter and feeding opportunities. Inland wetlands are recorded as primary habitat in the IUCN assessment. The basin's subtropical latitude means seasonal temperature variation is more pronounced than in equatorial Amazonian drainages.
Feeding
Hemigrammus brevis is an omnivore in the manner typical of small characids throughout South America. In the wild it feeds on small aquatic and terrestrial invertebrates, including insect larvae, microcrustaceans, and items taken from the water surface, supplemented by algae and fine organic material.
In the aquarium it readily accepts high-quality prepared foods — flake and micro-pellets — alongside live and frozen foods such as Daphnia, brine shrimp nauplii, and Cyclops. Small, frequent feedings suit its size and activity level. A varied diet maintains condition and encourages natural coloration.
Mating
Hemigrammus brevis follows the egg-scattering reproductive strategy universal among Hemigrammus tetras. Males display to females using lateral presentation and fin erection, intensifying coloration where present. There is no pair bond and no territorial defence beyond momentary courtship interactions; spawning occurs in the open water column or among fine-leaved vegetation.
Displaying males court receptive females by shadowing them through vegetation and initiating spawning drives into plant thickets or over submerged surfaces. The species shows no parental behaviour and eggs receive no attention from adults after deposition.
Breeding
Like other Hemigrammus, H. brevis is an open egg-scatterer with no parental care. Spawning occurs among fine-leaved plants or over soft substrate, where small, adhesive eggs are deposited during brief spawning drives. Adults pay no attention to eggs after spawning and will consume them if given the opportunity, making removal of adults or eggs to a separate rearing vessel the standard practice for anyone wishing to raise fry.
Eggs hatch within one to two days at typical tropical temperatures, and the resulting fry are tiny and require very fine initial foods — infusoria or commercial liquid fry food — before they are able to take newly hatched brine shrimp. No specialised conditioning or unusual water chemistry is required for this species to spawn, consistent with the straightforward breeding behaviour of the genus as a whole.
In the aquarium
Hemigrammus brevis is infrequently encountered in the aquarium trade and is rarely the subject of dedicated hobby literature; no care guide was located during research for this profile. General Hemigrammus husbandry applies: a small, peaceful schooling tetra best kept in groups of six or more in a planted aquarium with soft, slightly acidic to neutral water and subdued lighting, though it likely tolerates a wider range given the subtropical and more variable character of the São Francisco system.
Its small size makes it suitable for nano and community aquaria alongside similarly sized peaceful species. Good filtration with gentle flow, regular partial water changes, and a varied diet of small prepared and live or frozen foods will keep the fish in good condition. As with most small tetras, it benefits from the visual security of being kept as a proper school rather than in small numbers.
Conservation
Hemigrammus brevis is assessed as Least Concern (LC) on the IUCN Red List, with the assessment completed in 2022 and the population trend recorded as stable. The species' range across the São Francisco River basin is broad relative to many small stream tetras, and no severe ongoing decline has been documented.
The IUCN assessment notes threats including logging and wood harvesting in the catchment, and domestic and urban wastewater affecting water quality — pressures common to much of the São Francisco basin. These threats are real but not judged sufficient at present to elevate the species above Least Concern. The São Francisco basin faces ongoing deforestation, agricultural expansion, and water extraction pressures that could affect habitat quality over time, but H. brevis currently holds a stable conservation status across its native range.