Taxonomy & naming
Cyphocharax biocellatus was described in 2012 by Richard P. Vari, Brian L. Sidlauskas and Philippe Le Bail as one of several new Cyphocharax species erected from Suriname and French Guiana material. It belongs to the family Curimatidae, the "toothless characins," a large Neotropical group within Characiformes whose members lack functional jaw teeth as adults, an adaptation tied to their detritivorous, substrate-grazing lifestyle. The genus Cyphocharax is one of several curimatid genera recognised by the Catalog of Fishes (Eschmeyer, California Academy of Sciences) as the valid framework for this family, and it is distinguished from closely related genera such as Curimata and Steindachnerina largely by details of squamation, fin-ray counts and the shape of the mouth and gut.
The species epithet biocellatus refers to a paired eye-like marking (see Etymology below), a feature used alongside body proportions and scale counts to separate it from congeners in the same 2012 revision. As with many recently described, narrow-range curimatids, C. biocellatus is not a fish most aquarists or even many ichthyologists will have encountered outside its original description and subsequent regional faunal surveys.
Morphology
Cyphocharax biocellatus is a small, slender-bodied characin reaching a maximum recorded length of just 2.5 in standard length, making it one of the more modest members of a family that itself rarely produces large fish. Like other curimatids it has a small, subterminal, toothless mouth adapted for grazing rather than grasping, a torpedo-shaped body built for holding position in current, and the plain silvery countershading typical of small riverine characins.
The name-giving feature is a distinctive double eye-like marking (bi- "two" + ocellatus "eyed/spotted") used by the describing authors to help separate this species from its close Cyphocharax relatives; beyond that diagnostic marking, detailed live colouration and any sexual differences in shape have not been documented in accessible literature, and this article does not speculate beyond what the original description and subsequent citations record.
Habitat
The species is known from the Marowijne (Maroni) River system spanning eastern Suriname and western French Guiana, with additional records from the Mana basin in French Guiana — a narrow endemic range confined to the Guiana Shield. Its type locality is a side channel of the Litani River, a Marowijne tributary, over shallow cataracts of bedrock and boulders, and its broader habitat is described as shallow tributary reaches with rapid flow over sandy substrate, rocky bars and fallen wood, generally in water less than two metres deep.
This is a fast-water, hard-substrate habitat rather than the slow blackwater floodplain typical of many other Neotropical characins, and it places C. biocellatus among the many small Guiana Shield fishes whose entire known range sits within a handful of tributary systems draining ancient crystalline bedrock.
Feeding
No species-specific dietary study of Cyphocharax biocellatus is available, but its family membership is strongly diagnostic: Curimatidae are detritivores that graze films of algae, biofilm, slime and fine organic detritus from rock and sand surfaces using a toothless, sediment-processing mouth and gut, and in some South American river systems curimatids collectively make up roughly half of total fish biomass, underscoring how important this grazing role is in Neotropical river food webs.
Given its rocky, current-swept habitat, C. biocellatus almost certainly forages by working the biofilm on boulders and cobble rather than sifting soft floodplain mud, consistent with its congeners' documented behaviour.
Mating
Nothing specific has been published on courtship behaviour in Cyphocharax biocellatus. Research on other, better-studied curimatids from temperate and subtropical South American rivers has noted a rise in feeding activity ahead of the reproductive period, which the describing literature on this family suggests as a plausible general pattern across the genus, but this has not been confirmed for C. biocellatus itself, and no sexual dimorphism has been documented for the species.
Breeding
There is no confirmed, published breeding account for Cyphocharax biocellatus, in the wild or in captivity, and this article will not assign it a spawning mode it has not been documented performing. Curimatids as a family are generally understood to be open-water or scatter egg-layers with no parental care, consistent with most small riverine characins, but that pattern has not been specifically verified for this species, and it has essentially no history in the aquarium hobby from which to draw observations. Data is sparse here, and that gap should be stated plainly rather than filled in.
In the aquarium
Cyphocharax biocellatus is not an established aquarium fish; it does not appear to be traded or kept with any regularity, and this account should not be read as a proven care sheet. Based on its small adult size (under 3 in) and its fast, well-oxygenated, rocky-bottomed native habitat, a hypothetical setup would call for a modest shoaling group, strong water movement, a sand-and-stone substrate to graze, and clean, well-oxygenated water rather than a still, planted community tank — but this is inference from its biology and its family's general husbandry, not a tested protocol.
Any curimatid kept at home should be given algae- and detritus-rich grazing surfaces alongside prepared foods, since a toothless, biofilm-adapted mouth is poorly suited to being fed like a typical omnivorous tetra.
Conservation
The IUCN Red List assessed Cyphocharax biocellatus as Near Threatened (NT) on 12 March 2023, under criterion B1b(iii,v), reflecting its very restricted range — essentially the Marowijne/Maroni and Mana basins of the Suriname–French Guiana border region — which leaves it vulnerable to any localised habitat degradation despite no immediate population crisis being documented. As with many single-region Guiana Shield endemics, the concern is one of limited range and exposure rather than an active, ongoing decline, and the species is not known to be targeted by the aquarium trade, which removes one common pressure on small range-restricted characins.