Taxonomy & naming
Creagrutus anary was described by the American ichthyologist Henry Weed Fowler in 1913. The valid name and original authorship are recorded in Eschmeyer's Catalog of Fishes, which is the governing authority for valid names used on this site. The species belongs to the genus Creagrutus, a large assemblage of small, streamlined characids distributed broadly across the rivers of South America. Creagrutus itself has a complex taxonomic history and contains many species that are morphologically similar and difficult to distinguish without careful meristic examination.
FishBase and other modern aggregators list this species in the family Stevardiidae — a family erected to accommodate a subset of the former Characidae after molecular phylogenetic work. However, the top-level family field for this article follows the instructions for the tetras section of this atlas and is recorded as Characidae, the broader family sensu lato in which the genus has traditionally sat.
The specific epithet anary is a local Brazilian common name for the fish, reflecting a tradition of using vernacular regional names as species epithets in the original description. The genus name Creagrutus derives from the Greek for 'to tear or rip up flesh', a reference to the dentition of early-described members of the genus rather than an accurate description of the mild-mannered fish encountered in the aquarium.
Morphology
Creagrutus anary is a small, elongate characid reaching a maximum of 2 in standard length according to FishBase. Like other members of the genus, it has the typical streamlined build of a benthopelagic forager: a moderately compressed body, a subterminal to terminal mouth suited for picking invertebrates from substrate and mid-water, and the small adipose fin characteristic of Characiformes.
The coloration is modest by aquarium-fish standards. Members of Creagrutus typically display a silvery body with a dark lateral stripe or band running from behind the gill cover toward the caudal peduncle, a pattern that provides camouflage in dappled, tannin-stained Amazonian waters. Fin coloration is generally plain. Sexual dimorphism is subtle and not well documented in the literature for this species specifically; in related Creagrutus the sexes differ mainly in body depth, with ripe females becoming noticeably more rounded.
Habitat
The species is native to the Madeira River basin, one of the largest and most biodiverse drainages in the Amazon system, draining parts of Bolivia and Brazil. Within that basin, Creagrutus species are characteristically associated with smaller tributaries, headwater streams, and marginal habitats rather than the main channel, foraging in the benthopelagic zone — close to the bottom and in open water — among leaf litter, submerged wood, and root masses.
Water conditions across the Madeira basin range from soft and acidic in blackwater and clearwater tributaries to somewhat harder and more neutral in white-water reaches. Congener data and general Amazonian characoid ecology suggest this species is most at home in water with temperatures around 72–79 °F, pH between 6.0 and 7.2, and low to moderate hardness. Tropical lowland streams in this region are typically warm year-round, with seasonal fluctuations in water level that may influence spawning behaviour.
Feeding
Creagrutus anary has a trophic level of 2.5 recorded in FishBase, placing it at the base of the food chain as a consumer of small invertebrates, organic detritus, and plant material. In the wild, Creagrutus species are known to forage along the substrate and in open water for small aquatic invertebrates — insect larvae, microcrustaceans, worms — as well as terrestrial invertebrates that fall into the water.
In the aquarium, it can be expected to accept most small prepared foods: good-quality micro-pellets, finely crushed flake, and frozen or live foods such as Daphnia, micro-worm, and baby brine shrimp. As with many small characids, a varied diet that includes live or frozen invertebrate prey will keep the fish in better condition and colour than a diet of dry food alone. It is not a predator of other fish of similar size and is safe in a well-chosen community.
Mating
No specific reproductive behaviour has been described in the scientific literature for Creagrutus anary. Based on the general biology of Neotropical characids and published accounts of closely related Creagrutus species, the species is presumed to be an egg-scattering open spawner. Males likely court females with brief chasing displays in open water or among fine-leaved vegetation, releasing sperm as the female broadcasts eggs.
Spawning in the wild may be seasonally triggered by changes in water level, temperature, or photoperiod associated with the Amazonian wet season, when rising floodwaters create temporary spawning and nursery habitat in flooded forest. In the aquarium, conditioning pairs or small groups with live and frozen foods and simulating a slight drop in temperature and water hardness (mimicking the onset of the rainy season) may encourage spawning activity.
Breeding
Creagrutus anary has not been bred in captivity and documented in the hobbyist or scientific literature to any meaningful degree. As a general egg-scattering characid, however, the approach that works for many small tetras should be attempted: a small, dimly lit breeding tank with a fine-leaved plant or spawning mop, soft and slightly acidic water (pH around 6.5, hardness low), and a temperature in the mid-20s Celsius. Adults should be conditioned on live and frozen foods for several days before introduction to the breeding tank.
Eggs, once scattered among the plants or mop fibres, should be removed from the adults, which will consume them. Incubation in typical Neotropical characids takes 24–72 hours at around 79 °F, with fry becoming free-swimming after a further two to three days. First foods for the tiny fry would be infusoria or commercial liquid fry food, followed by newly hatched brine shrimp as the fry grow. No parental care is offered at any stage.
In the aquarium
Creagrutus anary is a rare fish in the aquarium trade and is not commonly available. Hobbyists who acquire it will find a small, peaceful, and undemanding fish well suited to a biotope or planted community aquarium themed around Amazonian or broadly South American conditions. A group of six or more will be more active and show more natural behaviour than isolated individuals, as with most small schooling characids.
Water should be soft to moderately soft and slightly acidic to neutral, with a temperature in the 72–79 °F range. The tank should be well filtered but not overly turbulent, with areas of shade created by floating plants or overhanging vegetation. The species is compatible with other small, peaceful fish of similar size — small tetras, dwarf cichlids such as Apistogramma, small corydoras — and will not disturb invertebrates large enough not to be eaten. Because of its obscurity in the hobby, accurate information on long-term care is limited; treating it as one would treat other small Amazonian tetras is a sound starting point.
Conservation
Creagrutus anary was assessed as Least Concern (LC) on the IUCN Red List in November 2018. The Least Concern designation reflects the species' occurrence in the Madeira River basin, a vast drainage that, despite pressures from deforestation, agriculture, and hydroelectric development, still contains large areas of intact habitat. A wide distribution within a large basin generally buffers a species against the kind of range-restricted decline that elevates threat levels.
Nonetheless, the Madeira basin faces significant and ongoing anthropogenic pressure. Large dams on the main stem of the Madeira River in Brazil have altered hydrology, blocked migratory fish, and changed sediment regimes in ways that affect river ecology broadly. Deforestation in the Bolivian and Brazilian portions of the basin continues, increasing sedimentation and water temperature in affected streams. For a small, benthopelagic tetra dependent on structurally complex stream habitats, these pressures bear watching. The IUCN assessment should be revisited as more data on the species' precise distribution and population trends become available.