Taxonomy & naming
Creagrutus magoi was formally described by Richard P. Vari and Arthur S. Harold in 2001. The valid name, as recognised in Eschmeyer's Catalog of Fishes (Catalog of Fishes, CAS), is Creagrutus magoi Vari & Harold, 2001. The genus Creagrutus belongs to the family Characidae and is placed within the subfamily Stevardiinae (sometimes treated as the family Stevardiidae) — a large and taxonomically complex group of characid fishes distributed across Central and South America. Creagrutus itself is a species-rich genus of small, streamlined tetras with numerous described species across the northern Neotropical region.
The specific epithet magoi is a patronym honouring Francisco Mago Leccia (1931–2004), a Venezuelan ichthyologist who made foundational contributions to the study of the freshwater fishes of Venezuela. Records confirm the species in both Venezuelan and Colombian ichthyology literature, including checklists of Colombian freshwater fishes (Lasso et al. 2004; Maldonado-Ocampo et al. 2006).
Morphology
Creagrutus magoi is a small, slender-bodied characid reaching approximately 2.5 in standard length. Like other members of the genus, it displays the streamlined, fusiform body plan typical of fast-water characids, with a moderately compressed profile suited to life in flowing streams. The genus Creagrutus is characterised by features including a slightly oblique mouth, moderate-sized scales, and a typical characid complement of fins including a small adipose fin.
Data on the precise colour pattern, meristic counts, and other diagnostic morphological details of Creagrutus magoi specifically are sparse in the available sources. As is common in the genus, adults are likely silvery with subdued lateral markings; definitive morphological distinctions from congeners are established in the original description. Sexual dimorphism, if present, has not been documented in the available literature.
Habitat
Creagrutus magoi inhabits freshwater rivers and streams associated with the Guiana Shield of northern South America. Its documented range spans Venezuela and Colombia, with records from the Guiana Shield and indications of occurrence in the Magdalena River basin of Colombia. The species occupies tropical freshwater systems and has been associated with swift-flowing water, a typical habitat for stream-dwelling Creagrutus species.
Water chemistry data from Guiana Shield fish communities suggest conditions of moderate acidity, with pH around 6.5 and temperatures near 77 °F (77 °F). As a Guiana Shield stream fish, it likely occurs among rocky substrates, leaf litter, and riparian vegetation in clear to moderately tannin-stained water. Precise locality and depth data for this species are not available in the surveyed sources.
Feeding
Creagrutus species are generally regarded as insectivores and micro-predators in their native streams, taking small aquatic invertebrates, insect larvae, and terrestrial insects that fall onto the water surface. This feeding guild is consistent with the streamlined body and active swimming habits seen across the genus in fast-water habitats of the Guiana Shield.
No species-specific dietary studies for Creagrutus magoi are available in the literature consulted. Based on congener data and habitat associations, the species likely forages opportunistically for small invertebrates in the water column and at the surface, typical of stream-dwelling characids in this region.
Mating
No specific observations of mating behaviour in Creagrutus magoi have been documented in the available sources. Based on the broader biology of stream-dwelling characids in the genus Creagrutus and the Guiana Shield, reproduction is expected to follow the egg-scattering pattern typical of characids: fish spawn in open water or among fine-leaved aquatic vegetation and submerged plant material, with no pair bond and no parental care of eggs or fry.
Spawning is thought to be seasonal in many Guiana Shield stream fishes, often timed to the onset of the rainy season when rising water levels, increased flow, and flooding of marginal vegetation create suitable conditions for egg deposition. Males likely school with females and release gametes without extended courtship display.
Breeding
No captive breeding records for Creagrutus magoi are known from the consulted sources, and the species is not established in the ornamental fish trade. Based on its placement within Characidae and the general biology of Creagrutus, breeding is expected to involve egg scattering among aquatic vegetation or over substrate, with adhesive or semi-adhesive eggs receiving no parental attention.
In wild populations of related Guiana Shield stream characids, spawning is believed to occur during shallow-water conditions associated with the rainy season, when flooded marginal zones provide cover for eggs and early larvae. Fry would be expected to be small at hatching and to require fine-particle food items in early life. Specific incubation times, clutch sizes, and fry care requirements for this species remain undocumented.
In the aquarium
Creagrutus magoi is essentially unknown in the aquarium hobby. It is not regularly imported or commercially available, and there are no established husbandry notes specific to this species. Its care requirements can be inferred from its ecology: a well-oxygenated aquarium with good flow, slightly acidic to neutral water (pH around 6.5–7.0), tropical temperatures in the mid-20s Celsius, and a diet of small live or frozen invertebrates such as Daphnia, brine shrimp, and bloodworm would likely suit it.
As a schooling stream fish from swift-flowing Guiana Shield waters, Creagrutus magoi would be expected to fare best in groups, in a tank with current and hiding spots among plants or driftwood. Given its small size and probable temperament, it would be compatible with other small, peaceful stream-dwelling tetras. Any aquarist encountering this species should treat it as a rare, wild-caught subject requiring careful acclimation and soft, well-oxygenated water.
Conservation
Creagrutus magoi is reported as Least Concern (LC) by FishBase, reflecting a current assessment that the species does not face significant range-wide extinction risk. No specific IUCN Red List assessment page was located for this species during research; the LC status is carried in the FishBase record without a cited assessment year or taxon ID.
The Guiana Shield is one of the most biodiverse freshwater regions on Earth and remains relatively intact compared to many lowland South American systems, which supports the presumption of stable populations for species such as Creagrutus magoi. Ongoing threats to Guiana Shield freshwater biodiversity include deforestation, mining, and water-quality degradation from artisanal and industrial extraction; whether these pressures specifically affect Creagrutus magoi populations is not documented in the available sources.