Taxonomy & naming
Cheirodon ortegai was described by Richard P. Vari and Jacques Géry in 1980. The valid name, as recorded by Eschmeyer's Catalog of Fishes, is Cheirodon ortegai Vari & Géry, 1980. The type locality is a woodland pool along the Río Ucayali at Cocha Lobo, 3 mi downriver from Masisea, Coronel Portillo Province, Loreto Department, Peru.
The genus Cheirodon is placed within the family Characidae, the largest family of freshwater fishes. The generic name derives from the Greek cheir (hand) and odous (teeth), a reference to a distinctive tooth shape found in members of this genus. Cheirodon ortegai is one of several small characins inhabiting the Ucayali drainage, and its restricted type locality in a floodplain woodland pool is typical of the microhabitats exploited by small-bodied Amazonian tetras.
Morphology
Cheirodon ortegai is a small, slender-bodied characin with a maximum recorded standard length of 1.5 in. Like other members of the genus it has the classic tetra body plan — a laterally compressed, fusiform profile with a forked tail, an adipose fin, and a complete lateral line — scaled at a size that keeps it among the smallest of its kind in its range.
Detailed meristic and coloration data for this species are sparse in the public literature. As a representative small Cheirodon it is likely silvery-bodied with the thin lateral stripe and hyaline fins characteristic of the group. The small tooth plates for which the genus is named are visible under magnification but not a field-identification feature. Sexual dimorphism, if present, is probably subtle and similar to other small characins in the genus.
Habitat
Cheirodon ortegai is recorded from the Ucayali River basin in Peru, with a range that extends into the Bajo Pachitea River basin (spanning Huanuco and Ucayali departments) and the lower Nanay River, a tributary of the Amazon near Iquitos. All confirmed localities fall within a low-elevation band of roughly 328–820 ft above sea level in Amazonian lowland Peru.
The IUCN assessment characterises its habitat as lotic (flowing) waters with sandy to muddy substrates — the broad category that encompasses Amazonian channels, flooded forest streams, and the woodland pools like the type locality at Cocha Lobo. The region experiences distinct wet and dry seasons that drive lateral flooding across the várzea, and small characins in this system typically exploit both main-channel margins and the seasonally inundated forest floor. The species has not been recorded outside Peru.
Feeding
Cheirodon ortegai is regarded as a diet generalist insectivore in the manner typical of small Cheirodon tetras. Aquatic insect larvae — particularly Diptera (midges and their relatives) — are the primary dietary component documented for the genus. Small adult insects taken at the surface and other invertebrates likely supplement the diet opportunistically.
In an aquarium setting, small Cheirodon species such as this accept a wide range of standard foods: fine flake, micro-pellets, and frozen or live foods including Daphnia, Cyclops, and finely separated bloodworm. As with most small characins, a varied diet that includes live or frozen invertebrate matter is beneficial for condition and any potential spawning attempt.
Mating
Detailed spawning observations for Cheirodon ortegai specifically are not documented in the available literature, but the biology of closely related small Cheirodon and the broader genus points to a consistent reproductive pattern. Small characins of this group are egg-scattering open spawners with no parental care, releasing adhesive eggs among fine-leaved aquatic plants or over the substrate.
Male display behaviour in small characins typically involves colour intensification and lateral posturing toward females and rival males. In seasonally flooded Amazonian systems like the Ucayali basin, spawning is often associated with rising water levels and the availability of inundated vegetation — the timing cue that most egg-scattering tetras use in the wild and that can be mimicked in captivity through a gradual temperature drop and water change.
Breeding
No captive breeding account specific to Cheirodon ortegai appears in the available sources. Based on the genus and subfamily, breeding in captivity would follow the standard small-tetra pattern: a conditioned group spawns over a dense clump of fine-leaved plants or a synthetic spawning mop, depositing small adhesive eggs that hatch in 24 to 48 hours at tropical temperatures. Adults show no parental care and will readily eat both eggs and freshly hatched fry.
For any attempt, separating the eggs or transferring the adults immediately after spawning is necessary. The tiny fry require infusoria or other first foods of equivalent size before graduating to newly hatched brine shrimp nauplii. Because this species is uncommon in the hobby and rarely exported, captive-breeding records from private keepers would be a valuable contribution to the literature.
In the aquarium
Cheirodon ortegai is rarely encountered in the aquarium trade and is primarily of interest to specialists in small Amazonian characins. When available, it would be suited to a softwater, planted nano aquarium in the style appropriate for small Peruvian tetras: warm (around 75–82 °F), slightly acidic to neutral water, dim or filtered lighting with shaded patches, and a dark substrate that brings out the natural coloration of small silvery tetras.
As a small schooling species it should be kept in groups of at least six. Tankmates, if any, should be similarly tiny and non-aggressive — other micro-tetras, small Corydoras, or dwarf otocinclus would be appropriate. The low bioload of fish this size allows a well-planted aquarium of even modest volume to maintain a stable, healthy group. Given its scarcity in commerce, specimens are most likely to be encountered through specialist importers or ichthyological hobbyist networks.
Conservation
Cheirodon ortegai is assessed as Least Concern (LC) on the IUCN Red List, with the assessment published in 2016 based on a 2014 evaluation by Hernán Ortega Torres and E. Correa — the species' namesake among the assessors. The population trend is reported as stable, and no major threats are identified. Although the species has a restricted distribution within Peru, the IUCN assessment notes that there are no conservation measures in place and the species does not occur within known protected areas.
The low profile of this small, inconspicuous fish in the ornamental trade means collecting pressure is not considered a significant concern. The main long-term risk, as for most Amazonian endemic fishes, is habitat degradation from deforestation and watershed alteration in the Ucayali and Pachitea basins. Its relatively small documented range makes the species one to monitor if land-use change in that part of Loreto and Ucayali departments accelerates.