Taxonomy & naming
Ctenobrycon kennedyi was described by Carl H. Eigenmann in 1903, and is recognised as a valid species in the genus Ctenobrycon within the family Characidae. The type series comes from South American drainages, and the species is recorded from the Paraguay and São Francisco River basins. Eschmeyer's Catalog of Fishes confirms the valid name as Ctenobrycon kennedyi (Eigenmann, 1903); the parenthetical authority reflects that the species was originally placed in a different genus. No synonyms are recorded.
The genus Ctenobrycon belongs to the large and taxonomically intricate order Characiformes. FishBase and related authorities have associated the broader American tetra assemblage with revised family-level arrangements, and some sources place the genus within or near Acestrorhamphidae — a grouping that reflects ongoing revisions to higher-level characiform classification. The Catalog of Fishes remains the definitive reference for the valid placement at species level.
Morphology
Ctenobrycon kennedyi is a small, slender-to-moderately-deep-bodied characid with a maximum recorded standard length of 2.5 in. Like most members of its genus it displays the typical characid body plan: a compressed, somewhat oval lateral profile, a forked tail, a short adipose fin, and moderately large eyes placed high on the head.
Detailed colour descriptions for wild specimens are sparse in the available literature. As with many small tetras, the ground colour is likely silvery with iridescent flanks, possibly carrying a lateral stripe or spot common to close relatives. Sexual dimorphism has not been described in detail in accessible sources, though slight female fullness at maturity would be typical for the group. Data on specific meristic characters — scale counts, fin-ray formulae — are not reproduced here, as those details were not captured in the cached sources.
Habitat
Kennedy's tetra is endemic to South America, with distribution records from the Paraguay River basin and the São Francisco River basin. These are two geographically separated drainages spanning a large swath of Brazil and adjacent countries, suggesting the species tolerates a range of interior lowland freshwater habitats.
FishBase records it as a benthopelagic freshwater fish, inhabiting calm to moderately flowing waters. Preferred water conditions in the wild are soft and acidic: pH 5.5–6.8, hardness 0–12 dH, and temperature 72–82 °F. These parameters are consistent with the blackwater and clearwater stream habitats typical of interior South American drainages, where leaf litter and low mineral content produce the soft, tea-coloured water that many small characids favour.
Feeding
FishBase assigns Ctenobrycon kennedyi a trophic level of 2.8, consistent with an omnivorous diet skewed toward zooplankton and small invertebrates. In the wild, small tetras of this size class typically feed on microcrustaceans, aquatic insect larvae, small terrestrial insects that fall to the surface, and algae or fine organic matter.
In the aquarium it can be expected to accept a broad range of prepared foods — quality flake and micro-pellets — supplemented with frozen or live foods such as Daphnia, brine shrimp, and bloodworm. A varied diet supports condition and colouration. Its trophic level and resilience rating (minimum population doubling time under 15 months) suggest a generalist feeder capable of thriving on the foods readily available to most aquarists.
Mating
Specific courtship observations for Ctenobrycon kennedyi are not documented in the cached sources. As a member of Ctenobrycon and the broader characid assemblage, the species can be expected to follow the open egg-scattering strategy typical of the group: males court receptive females with active pursuit and lateral displays, and spawning takes place over fine-leaved vegetation or other suitable substrate.
Limited hobbyist reports indicate that social schooling behaviour is observed in the aquarium, and that the fish responds well to group conditions. As with most tetras, condition and water quality are likely the primary triggers for spawning behaviour; soft, slightly acidic water mimicking the species' natural habitat would be expected to encourage courtship.
Breeding
Breeding has been reported in captivity, though detailed accounts are scarce. The reproductive mode is standard for small characids: egg scattering with no parental care. Adults will consume their own eggs, so eggs or spawning medium should be removed to a separate rearing vessel promptly after spawning.
Eggs are adhesive and typically deposited among fine-leaved plants, Java moss, or synthetic spawning mops. Incubation at typical tropical temperatures (72–82 °F) follows a timeline consistent with small characids — generally a few days to hatch, with fry becoming free-swimming shortly after. First foods for the tiny fry would need to be very fine — infusoria, rotifers, or commercial liquid fry food — before graduating to newly hatched brine shrimp. Full breeding details remain sparsely documented for this species; aquarists with experience breeding the species would expand knowledge considerably.
In the aquarium
Kennedy's tetra is described in hobbyist sources as a moderate-care species that adapts reasonably well to aquarium conditions. Although its wild preference is for soft, acidic water (pH 5.5–6.8, 72–82 °F), hobbyist reports indicate it adjusts to neutral water in captivity, broadening its suitability for a range of setups.
As a social species, it should be kept in a school of six or more individuals. A well-planted aquarium with subdued lighting and dark substrate will highlight its natural colouring and reduce stress. Tankmates should be similarly sized and peaceful — other small tetras, small corydoras, and dwarf cichlids from compatible parameter ranges are logical companions. The species' small adult size means a tank in the range of 23.5–31.5 in is adequate for a school. It is not prominently available in the mainstream trade, but may be encountered through specialist importers or breeders.
Conservation
Ctenobrycon kennedyi is assessed as Least Concern (LC) on the IUCN Red List, with the assessment dated 4 March 2021. The species' presence across two major South American river basins — the Paraguay and the São Francisco — likely contributes to the stable assessment: wide-ranging interior-drainage tetras without specific habitat restrictions tend to maintain viable populations across large areas.
FishBase notes a high resilience rating with a minimum population doubling time of less than 15 months, which is consistent with small, r-selected characids that mature quickly and produce multiple spawns. No significant threats to the species are highlighted in the cached sources. Standard pressures on South American freshwater biodiversity — deforestation, watershed degradation, and pollution of interior drainages — represent background concerns for the family broadly, but Kennedy's tetra currently shows no indication of population decline.