Taxonomy & naming
Creagrutus paralacus was formally described by Anita S. Harold and Richard P. Vari in their 1994 monograph on the Trans-Andean species of Creagrutus, published as Smithsonian Contributions to Zoology number 551. The type locality is the Río Táchira, within the Río Catatumbo basin, which drains into Lake Maracaibo in Venezuela. Eschmeyer's Catalog of Fishes (Catalog of Fishes, CAS) recognises the name as valid under the authority Harold & Vari, 1994.
Creagrutus is a large and diverse genus of characids placed in the family Characidae. The Trans-Andean species of the genus — those occurring west of the Andes, in the lake and river drainages of western Venezuela and adjacent Colombia — were shown by Harold and Vari to form a coherent group, and C. paralacus belongs to that Trans-Andean assemblage. The genus name Creagrutus is of Greek derivation (kreas, flesh; agrutēs, hunter or collector), applied by Günther in the original description. The specific epithet paralacus is a Latin compound meaning 'beside the lake', an allusion to the species' occurrence in tributaries peripheral to Lago Maracaibo.
Morphology
Creagrutus paralacus is a small characid, reaching a maximum recorded standard length of 2.5 in. Like other members of the genus, it has the compact, slightly fusiform body plan typical of small riverine characids, with a relatively short snout, a terminal to slightly subterminal mouth, and the characteristic adipose fin of the order Characiformes.
Detailed external morphology for this species is data-sparse in the available literature beyond what is captured in the original 1994 description. As a member of the Trans-Andean Creagrutus clade, it shares the general meristic and osteological characters used by Harold and Vari to diagnose that group, but species-level diagnostic features in the field are difficult to assess without reference to the original descriptive work. The species is benthopelagic in habit, occupying the lower and mid-water zones of its stream and river habitats.
Habitat
Creagrutus paralacus is known from the southern and southeastern tributaries of Lago Maracaibo in Venezuela, a drainage that includes the Río Catatumbo and its basin, where the type series was collected in the Río Táchira. Lake Maracaibo is one of the oldest and largest lake systems in South America, and its peripheral tributaries drain a mosaic of foothill and lowland terrain on the eastern Andean slopes and the surrounding plains.
The species occurs in permanent rivers and streams — benthopelagic in the water column rather than strictly benthic — within the tropical freshwater zone of the basin. The IUCN assessment notes an extent of occurrence of approximately 23,12 mi², confined to the Lake Maracaibo tributary system. Detailed habitat parameters for water temperature and chemistry at the collection sites are not captured in the available sources, but the region is broadly tropical with warm, lowland freshwaters.
Feeding
FishBase classifies Creagrutus paralacus as an omnivore with detritus among its recorded dietary components. This is consistent with the feeding ecology observed in many small-stream characids of South American lowland drainages, which tend to be opportunistic consumers of organic matter, small invertebrates, algae, and plant-derived detritus available in their benthopelagic zone.
More fine-grained dietary data for this species specifically are sparse in the accessible literature. The broad omnivore classification and benthopelagic lifestyle suggest it forages across the substrate and mid-water for whatever organic material and small invertebrates are available, a strategy common to Creagrutus and many allied genera in the Characidae.
Mating
No specific mating observations have been published for Creagrutus paralacus in the available literature. Reproductive biology for the species is essentially undescribed at the level of field or aquarium observation. Based on the broader biology of small characids in the family Characidae, open egg-scattering spawning without parental care is the expected mode, with adhesive or semi-adhesive eggs deposited among fine-leaved vegetation or substrate debris.
The species has not been documented in the aquarium hobby in a way that would have generated captive-breeding records. Until targeted field or aquarium work is done on this species, mating behaviour remains data-sparse.
Breeding
Breeding biology for Creagrutus paralacus is undescribed in the accessible literature. By analogy with closely related and ecologically similar small characids, the likely mode is egg-scattering open spawning with no parental care: eggs deposited among vegetation or substrate, with adults taking no role in guarding or attending eggs or larvae after spawning.
The species does not appear to be established in captive collections, and no aquarium breeding accounts are on record. Any extrapolation from the broader Characidae template — fine-leaved plant spawning, adhesive eggs, short incubation at tropical temperatures, fry initially hanging near the substrate before becoming free-swimming — should be treated as inference rather than observation specific to this taxon.
In the aquarium
Creagrutus paralacus is not an established aquarium species and is essentially absent from the ornamental trade. It is a scientifically described species known from museum collections and field surveys rather than from hobby keeping. Aquarists interested in Trans-Andean characids of the Maracaibo drainage would be more likely to encounter other small characids from the region than this species specifically.
Should it become available, the general care requirements of small South American riverine characids would apply: clean, well-oxygenated water, tropical temperatures, and a varied omnivore diet including small live or frozen foods alongside prepared diets. Its modest size (under 3 in SL) and benthopelagic habit would suit a species tank or a community with other small, peaceful South American fishes.
Conservation
Creagrutus paralacus is assessed as Least Concern (LC) on the IUCN Red List, based on an evaluation by Reis and Lima published in 2009 from an assessment conducted on 1 March 2007. The assessment notes a stable population and acknowledges the species' resilience relative to habitat modification, which is characteristic of several Creagrutus species. However, the IUCN assessment record itself flags the evaluation as 'Needs updating', indicating that the 2007 data may no longer fully reflect current conditions.
The Lake Maracaibo basin faces documented anthropogenic threats, including domestic and urban wastewater discharge and agricultural effluents identified in the IUCN notes as threats to C. paralacus. The basin supports significant human populations and agricultural activity, and water quality degradation is an ongoing concern. The extent of occurrence of roughly 23,0 mi² is restricted to the tributary network of a single lake system, limiting the buffer against basin-wide deterioration. An updated assessment would provide a clearer picture of whether the Least Concern rating remains appropriate.