Taxonomy & naming
Creagrutus maculosus was formally described in 2010 by Román-Valencia, García-Alzate, Ruiz-C., and Taphorn, based on material collected from the Güejar River drainage in the Orinoco Basin of Meta department, Colombia. The type locality is Pringamosal Creek, a tributary of the Güejar, at an elevation of 925 ft above sea level. The holotype is an adult male measuring 2.5 in standard length; 81 paratypes spanning 1–3 in SL were also designated from the same drainage.
The genus Creagrutus is a large, taxonomically complex assemblage of small South American characids in the family Characidae distributed across the Neotropical lowlands and foothills from Panama to the Río de la Plata system. Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & Fong) records Creagrutus maculosus Román-Valencia, García-Alzate, Ruiz-C. & Taphorn, 2010 as the valid name. The species is sympatric with the closely related C. calai in the Güejar system, and the original description carefully contrasted the two; C. maculosus is distinguished by its spotted flank pattern and the absence of fin hooks on males, characters that set it apart from other Creagrutus recorded from the region.
FishBase lists the species under the family Stevardiidae, reflecting a reclassification that some authorities recognise; however, following Eschmeyer's Catalog the broader Characidae treatment is retained here.
Morphology
Adults of Creagrutus maculosus are small, laterally compressed characids. The holotype male measured 2.5 in SL and paratypes ranged from 1–3 in SL, suggesting a maximum total length modestly above that range in fully grown individuals. The body shape is typical of the genus: elongate and slightly fusiform, with the profile of a generalised characin built for life in flowing water near the substrate.
The most distinctive external feature is the row of eight dark, rounded spots arranged along the sides of the body in adults, which gives the species its name and allows ready identification in the field. A dark stripe runs from behind the eye across the opercle. Scale counts place four to five rows of scales between the lateral line and the origin of the anal fin. Males lack the anal- and pelvic-fin hooks that are common in many Creagrutus congeners — the original description records the absence of hooks in males as a diagnostic character. No sexual dimorphism in body form or colour was noted by the original authors.
Habitat
The species is known from the Güejar River and its tributaries, including Pringamosal Creek, within the Orinoco Basin of Meta state in the Colombian Llanos foothills at the base of the La Macarena mountain range. The type locality sits at 925 ft above sea level, placing the species in piedmont streams rather than true Andean or lowland environments.
Habitat conditions recorded at the type locality include sandy substrates in the mainstream river channel, with tea-coloured water characteristic of blackwater or mixed-water drainages in the Colombian llanos. Water-quality parameters measured during collection were pH approximately 7.6 (with a recorded range of 5.0–7.6 across sampling sites), temperature 73–79 °F, and dissolved oxygen 6.5–7.3 mg/L. Depths ranged from 3–34 ft. The species occurred syntopically with Astyanax bimaculatus, Hyphessobrycon metae, and other characids typical of Orinoco piedmont drainages.
Feeding
No detailed dietary study of Creagrutus maculosus has been published. FishBase assigns a trophic level of 2.4, consistent with a benthopelagic, low-level consumer feeding on small invertebrates and organic material near the substrate, which is the generalised feeding mode seen across the genus Creagrutus.
By analogy with related species inhabiting similar piedmont stream habitats, the diet likely includes small aquatic invertebrates such as chironomid larvae and microcrustaceans, terrestrial insects falling onto the surface, and possibly algae and detritus. The benthopelagic habitat designation from FishBase is consistent with a species that forages in mid-water to near the bottom in flowing-water environments.
Mating
No specific observations of mating behaviour in Creagrutus maculosus have been published. The species has not been collected or bred in the aquarium hobby to a degree that would generate documented behavioural accounts. Based on the reproductive biology of Creagrutus and closely related characid genera, the species is presumed to be an egg-scattering open spawner that does not form pair bonds and provides no parental care.
The absence of fin hooks in males of C. maculosus is notable because hooks on the anal and pelvic fins of males are widespread in Creagrutus and related groups and are thought to play a role in contact spawning, where the male clasps the female during egg release. Their absence in this species may indicate a different spawning posture or simply a derived loss of the character, but no behavioural data are available to confirm this.
Breeding
Creagrutus maculosus is not recorded in the aquarium trade and has not been bred in captivity to the authors' knowledge; no aquarium breeding accounts appear in the published or hobby literature. The following is inferred from the biology of the genus and family.
As a characid, C. maculosus would be expected to scatter adhesive or semi-adhesive eggs among fine-leaved plants or substrate materials, with no parental care and active predation on eggs by adults. Incubation temperatures consistent with its habitat profile (72–79 °F) would be relevant for any future captive work. Data on clutch size, incubation period, and larval development remain unknown.
In the aquarium
Creagrutus maculosus does not appear in the ornamental fish trade and is not kept in home aquaria. The genus Creagrutus as a whole is rarely encountered in the hobby; its members are modestly sized, often drabber than flashier characids, and originate from collection localities not routinely served by the commercial trade.
Were the species to become available, its habitat data suggest an aquarium in the low-to-mid 20s Celsius, slightly acidic to near-neutral water (the field pH range was 5.0–7.6), and a moderate current with soft, sandy substrate would approximate conditions at the type locality. Because no aquarium accounts exist, any specific recommendations remain speculative.
Conservation
Creagrutus maculosus is assessed as Least Concern (LC) on the IUCN Red List, with the assessment completed on 11 November 2020. The LC listing reflects that the species is not considered to be declining at a rate that would qualify it for a threatened category, and no major range-wide threats have been identified that would warrant higher concern at the time of assessment.
The species is confirmed from Colombia — specifically Meta state in the Orinoco Basin — and is included in the Checklist of freshwater fishes of Colombia. The Güejar River and its piedmont tributaries lie in a region that includes protected landscapes associated with the La Macarena mountain range, which may afford some habitat security, though the species' actual population size and range extent within the Orinoco drainage remain poorly documented.