Taxonomy & naming
Creagrutus planquettei was described by Jacques Géry and Jean-François Renno in 1989 on the basis of material from the Approuague River system of French Guiana. The species was subsequently redescribed by Vari and Harold (2001:191), who provided a detailed morphological diagnosis. Eschmeyer's Catalog of Fishes (Catalog of Fishes, CAS) is the authority for the valid name Creagrutus planquettei Géry & Renno, 1989.
The genus Creagrutus belongs to the family Characidae. FishBase notes that recent classification assigns some Creagrutus relatives to the subfamily-level grouping Stevardiinae, but the family-level assignment remains Characidae. Creagrutus is a diverse Neotropical genus containing small, often cryptically patterned characins distributed across river drainages from Central America to southern South America.
Morphology
Creagrutus planquettei is a small characin reaching a maximum recorded length of 2.5 in standard length (SL), as reported in FishBase. Like other members of Creagrutus, it is laterally compressed and exhibits the characteristic body form of a small Neotropical characin — a relatively streamlined profile suited to flowing riverine habitats.
The morphological diagnosis provided by Vari and Harold (2001) distinguishes this species from congeners. Specific meristic and pigmentation details from that redescription define it within the genus; in overall gestalt it shares the small size and subdued colouration typical of the genus. The trophic level reported for this species is 2.4 (FishBase), consistent with a largely invertivorous or omnivorous diet near the base of the food web.
Habitat
The species is known exclusively from the middle and upper Approuague River basin in French Guiana, making it one of the more geographically restricted members of its genus. The Approuague is a blackwater-influenced river system draining the interior of French Guiana toward the Atlantic coast. Its forested catchment provides the shaded, leaf-littered stream habitats typical of Guiana Shield drainages.
FishBase records the species as a freshwater, benthopelagic, tropical fish — living and feeding close to the substrate or in the lower water column of its native streams. The combination of a naturally small range and apparent rarity within that range has driven the IUCN Vulnerable assessment. Planquette et al. (1996) provided the foundational baseline for freshwater fish distribution in French Guiana, against which subsequent surveys of Approuague fauna have been measured.
Feeding
A trophic level of 2.4 places Creagrutus planquettei as a low-level consumer, consistent with a diet of small invertebrates, microcrustaceans, aquatic insect larvae, and organic detritus typical of small Neotropical stream characins. The benthopelagic lifestyle inferred from FishBase data suggests it forages near the substrate as well as in the water column.
No specific stomach-content or dietary studies for this species appear in available sources. Its feeding biology is likely similar to other small Creagrutus: opportunistic foraging on whatever small invertebrate prey is available in the leaf litter and stream-bottom microhabitats it inhabits.
Mating
No specific mating observations or breeding data have been published for Creagrutus planquettei. The species is rarely encountered, and there are no records of aquarium spawning in the available literature. As a small characi in of the family Characidae, the expected reproductive strategy — by analogy with the broader family — would be open-water egg scattering with no parental care, but this has not been confirmed for this species specifically.
Males of small Creagrutus species may show subtle secondary sexual characters in the form of modified fin-ray hooks, a feature seen in various Characidae, though whether C. planquettei exhibits this has not been documented in accessible sources.
Breeding
No captive breeding records for Creagrutus planquettei are known. Its rarity in its native range and the general absence of this species from the ornamental fish trade mean that captive observations do not exist in the available literature.
By family-level inference, small Characidae such as Creagrutus are typically open-water egg-scatterers that deposit adhesive or semi-adhesive eggs among fine-leaved plants or substrate detritus, with no parental care offered after spawning. Water temperature, egg incubation period, and fry care requirements remain undocumented for this species specifically — data are sparse and any further detail would be speculation.
In the aquarium
Creagrutus planquettei is essentially absent from the ornamental fish trade and is not kept by hobbyists in any documented capacity. Its small size (to 2.5 in SL), benthopelagic habits, and presumed preference for the soft, acidic, tannin-stained waters of Guiana Shield stream systems would make it theoretically manageable in a well-filtered, shaded blackwater aquarium if specimens were obtainable.
Given the species' Vulnerable status and restricted range, collection for the aquarium trade would be an inappropriate use of a rare wild population. No husbandry notes, tank-size recommendations, or dietary observations from captivity are available in the literature.
Conservation
Creagrutus planquettei is assessed as Vulnerable (VU) under criterion B1ab(iii) on the IUCN Red List, with the assessment published on 14 December 2020. The Vulnerable listing reflects the species' limited extent of occurrence — confined to the middle and upper Approuague River basin in French Guiana — combined with inferred continuing decline in the quality of its freshwater habitat. Criterion B1ab(iii) specifically flags declining area, extent, or quality of habitat as a driver.
FishBase describes the species as rare. The Approuague drainage, while relatively intact compared to heavily deforested regions, faces pressures from gold mining (a significant issue across interior French Guiana), logging, and road development in the river's catchment. A species with a naturally small range is inherently sensitive to such pressures, and the combination of rarity and range restriction that characterises C. planquettei leaves little buffer against further habitat degradation.