Taxonomy & naming
Hyphessobrycon mamuruensis was described by Faria, Oliveira, Monteiro & Lima in 2025, with the original description published in Neotropical Ichthyology (volume 23, issue 3, article e240073). The type locality is the upper rio Mamuru basin, State of Pará, near the border with Amazonas State, Brazil. Eschmeyer's Catalog of Fishes recognises the valid name as Hyphessobrycon mamuruensis Faria, Oliveira, Monteiro & Lima, 2025, placed in the family Acestrorhamphidae (subfamily Hyphessobryconinae) under current higher-level classification; the top-level family field on this site follows Catalog of Fishes usage.
The genus Hyphessobrycon is one of the most species-rich in the order Characiformes, comprising several hundred small tetras distributed across tropical and subtropical South and Central America. The authors note that H. mamuruensis resembles two congeners, though precise details of those closest relatives require consulting the original description. No common names have been recorded for the species.
Morphology
Hyphessobrycon mamuruensis is a small, fusiform and laterally compressed tetra, reaching a maximum recorded standard length of 1.5 in. FishBase records 8–9 dorsal soft rays and 18–22 anal soft rays, meristic counts that assist in distinguishing it from closely related congeners.
Beyond these measurements the published data are sparse. The body plan is consistent with the typical small Hyphessobrycon form: a streamlined, schooling fish adapted to open water in shallow tributaries and forest streams. Specific colouration and detailed osteological or pigmentation characters are documented in the original description by Faria et al. (2025) but are not reproduced here.
Habitat
The species is known from the upper rio Mamuru basin in western Pará State, near the Pará–Amazonas border in north-central Brazil. The rio Mamuru is an Amazonian tributary, and the original description characterises the habitat as benthopelagic freshwater — clear to blackwater tributaries typical of the Amazonian lowland forest.
Tropical Amazonian streams of this type are typically warm, soft, and often slightly acidic, with dense riparian forest cover, leaf litter, and submerged woody debris providing shelter and feeding opportunities for small characids. FishBase classifies the species as tropical, consistent with the broader distributional pattern of Hyphessobrycon within the Amazon basin. No detailed in-situ habitat measurements for the type locality were available in the sources consulted.
Feeding
No specific dietary data for Hyphessobrycon mamuruensis have been published in the sources consulted. As a small benthopelagic tetra from Amazonian clear and blackwater forest streams, it almost certainly feeds opportunistically on small invertebrates — insect larvae, microcrustaceans, and zooplankton — as is typical for Hyphessobrycon congeners of similar size and habitat.
In an aquarium setting, small Hyphessobrycon tetras of this size class are generally undemanding, accepting finely crushed flake, micro-pellets, and small live or frozen foods such as Artemia nauplii, Daphnia, and micro-worms. Whether this species has yet been maintained in captivity by hobbyists is not recorded.
Mating
No specific reproductive behaviour data have been published for Hyphessobrycon mamuruensis. Members of Hyphessobrycon are characteristically egg-scattering open spawners with no parental care, and there is no reason to expect this species to differ from the family-wide pattern.
In typical Hyphessobrycon spawning, a conditioned male pursues the female through fine-leaved vegetation or spawning substrate, and the pair release small adhesive eggs that settle among plants or on the substrate. The adults take no further interest in the eggs or larvae. Given the species was only formally described in 2025 and appears not yet established in the hobby, breeding observations in captivity have not been reported.
Breeding
Captive breeding data for Hyphessobrycon mamuruensis are not available. Based on the reproductive mode universal to Hyphessobrycon, eggs would be expected to be small and adhesive, deposited among fine-leaved plants or spawning mops, with an incubation period and fry development broadly similar to other small tetras in the genus at tropical temperatures.
For comparably sized Hyphessobrycon species, breeders typically condition adults on varied live and frozen foods, spawn over Java moss or synthetic mops in a separate breeding tank, and remove adults after spawning to protect the eggs. Fry of small Hyphessobrycon are tiny at hatching and require infusoria or commercial liquid fry foods as first foods before advancing to newly hatched brine shrimp. Data specific to this species should be treated as absent until captive experience is documented.
In the aquarium
Hyphessobrycon mamuruensis has not been established in the aquarium hobby as of the time of writing. It was described from scientific collections in 2025 and no commercial or hobbyist availability has been recorded in the sources consulted.
Should it become available, husbandry expectations for a small Amazonian Hyphessobrycon of this size would follow the soft, warm-water approach appropriate for blackwater and clearwater tetras: low to moderate pH, soft water, temperatures in the mid-to-upper 20s Celsius, subdued lighting, and fine-leaved planting or dark substrate to make the fish comfortable. A schooling species of this size class is best kept in groups of six or more. Its small adult size of 1.5 in SL makes it suitable for nano and small planted aquaria alongside other diminutive, peaceful characids and small rasboras.
Conservation
Hyphessobrycon mamuruensis has not been assessed by the IUCN Red List. The species was only formally described in 2025, and assessments for newly described taxa typically lag by several years after publication.
Its known range is restricted to the upper rio Mamuru basin in Pará, a region where Amazonian forest faces ongoing pressure from agricultural expansion and land-use change. The restricted type locality and apparent endemism to a single drainage system suggest the species could be vulnerable to habitat disturbance, though without survey data on population size and extent of occurrence no formal assessment is possible. Continued taxonomic work on the diverse small-tetra fauna of the Amazon basin is needed to understand how many similarly range-restricted Hyphessobrycon await formal evaluation.