Taxonomy & naming
Cyphocharax gilbert was described by the French naturalists Jean René Constant Quoy and Joseph Paul Gaimard in 1824, placing it among the earliest-named members of its genus. It belongs to the family Curimatidae, the toothless "curimatas," within the order Characiformes — a family distinguished from its close relatives the Prochilodontidae (Prochilodus, Semaprochilodus) and the true piranhas and pacus of Serrasalmidae by its lack of functional jaw teeth and its gizzard-like, muscular stomach used for grinding fine organic material.
GBIF's taxonomic record confirms the current placement as Cyphocharax gilbert (Quoy & Gaimard, 1824), and the Catalog of Fishes governs the valid combination within Cyphocharax; the genus itself has undergone substantial revision over the last two centuries as curimatid taxonomy was reworked, which is typical for this speciose, historically under-studied family. Unlike the pacus and silver dollars of Serrasalmidae, Curimatidae has not seen the same recent wave of generic splitting, and gilbert has remained in Cyphocharax through the cache material reviewed here.
Morphology
Cyphocharax gilbert reaches a maximum recorded length of 9.5 in total length, a modest size consistent with most curimatids — this is a small-to-medium shoaling fish, not a large-bodied species like its distant Serrasalmidae relatives. As a member of Curimatidae it lacks functional oral teeth altogether; instead it relies on a muscular, gizzard-like stomach to grind down the fine algae and detritus it ingests, an adaptation shared across the family's grazing lifestyle.
Detailed external morphological description is not covered in the sources reviewed here, but curimatids as a group share a fusiform, laterally compressed, silvery body plan suited to open, turbid river channels and shoaling behaviour — consistent with the population data below, which records standard lengths in a wild population ranging from about 1–8 in.
Habitat
Cyphocharax gilbert is native to coastal river drainages of eastern Brazil, with FishBase recording its range from Bahia south through Rio de Janeiro and eastern São Paulo state — a coastal, rather than Amazonian or Orinocoan, distribution that sets it apart from many of the characins covered in this section. It is a freshwater, benthopelagic species found in ponds as well as river channels within this range.
A population ecology study on the Paraíba do Sul River system found this species preferring major rivers over 328 ft wide, at depths of 7–16 ft, with high turbidity, sand-mud substrates and dark water — a classic big-river, soft-bottom habitat rather than clear or heavily vegetated water. The subtropical latitude of its range (well south of the equator, into São Paulo and Rio de Janeiro states) means water temperatures here likely run cooler and more seasonal than in equatorial Amazonian systems, though the cache does not report specific temperature figures for this species.
Feeding
Cyphocharax gilbert is a toothless filter and detritus feeder, true to its family. The Paraíba do Sul River study describes it as consuming microscopic algae scraped and filtered from muddy riverbed sediment, processed through its gizzard-like stomach rather than chewed — there is no predatory or omnivorous component reported for this species in the sources reviewed.
This grazing strategy places C. gilbert among the "bottom of the food web" primary consumers in its river system, converting biofilm and fine organic matter into biomass that supports the predatory fish, birds and mammals that in turn eat it (see Conservation/ecology below). No aquarium feeding information is available in the cache; a fish of this type would be expected to need fine, sinking, vegetable-forward foods if it were ever kept, though it has essentially no aquarium-trade history to draw on.
Mating
Specific courtship behaviour for Cyphocharax gilbert is not documented in the sources reviewed. The Paraíba do Sul River study notes seasonal variation in reproductive intensity within the population, implying a defined breeding season tied to the river's annual hydrological cycle, but does not describe pairing, courtship displays or sexual dimorphism. Data is sparse here; no claims beyond what the population study reports can be made.
Breeding
The population study on the Paraíba do Sul River describes Cyphocharax gilbert as a multiple egg spawner with no parental care — consistent with the broadcast-spawning strategy typical of curimatids and many other small Neotropical river characins, rather than the nest-guarding behaviour of true piranhas or the foam-nest and migratory strategies seen elsewhere in this atlas section. Reproductive intensity varies seasonally within the studied population, tracking the river's flood cycle.
There is no evidence in the cache of this species being bred in aquaria, commercially or otherwise — it has essentially no aquarium-trade profile, and its reproduction is documented only through wild population ecology research rather than captive breeding accounts.
In the aquarium
Cyphocharax gilbert has no established presence in the aquarium hobby, and none of the sources reviewed here describe it being kept or bred in captivity. As a toothless, detritivorous grazer reaching around 9.5 in, it would in principle need a large, well-established tank with a soft sand-mud substrate, dim lighting and other peaceful shoaling tankmates, but this is inference from its biology rather than documented care experience — there is no hobbyist track record to draw on for this species.
Unlike the true piranhas (which need a real group and carry legal restrictions) or the pacus (which outgrow home tanks and must never be released), C. gilbert's relevant caution is simply that it is not a hobby fish: anyone encountering it would be dealing with a wild-collected or scientifically sourced specimen rather than a trade animal, and there is no reliable husbandry information to offer.
Conservation
The IUCN Red List assessed Cyphocharax gilbert as Least Concern in 2018, with FishBase noting medium resilience and a minimum population doubling time of 1.4–4.4 years. This reflects a species that, while restricted to eastern Brazilian coastal drainages rather than being widespread across South America, does not currently face elevated extinction risk.
Ecologically, C. gilbert plays a supporting role as prey for larger predators documented in the same river system, including the wolf fish Hoplias malabaricus and the migratory dorado Salminus maxillosus, as well as birds and otters — underscoring its place as a primary grazer near the base of the river food web rather than a species of direct conservation or fisheries interest in its own right. No specific threats are noted in the sources reviewed; general pressures on eastern Brazilian coastal river systems, such as damming and water-quality change, are the kind of long-term watch items relevant to a range-restricted river specialist like this one, though none are documented specifically for this species here.