Dianema urostriatus/longibarbis

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The Dianema urostriatus/longibarbis, also known as Flagtail Catfish, is a peaceful South American catfish recognized by its elongated body, long barbels, and darkly marked caudal fin. Associated with the quiet waters of the Brazilian Amazon, it spends much of its time near the bottom, searching the substrate for food. Its discreet but social behavior makes it suitable for a spacious community aquarium. Because this species is wild collected, careful acclimation and stable water conditions are especially important. Its availability remains moderate, making it an appealing find for aquarists interested in native Amazonian catfish.

General species description

Dianema urostriatus/longibarbis is an armored catfish in the family Callichthyidae. It is a bottom-dwelling, social, and generally peaceful species that uses its barbels to locate food in the substrate. It is most active at dusk or when the aquarium lights are dimmed. Keeping several individuals encourages natural behavior and reduces shyness. The species benefits from an aquarium with a large bottom area, hiding places, and effective filtration without excessive current. Fish offered to aquarists may be wild collected; quarantine and gradual acclimation are therefore sound practices.

Geographic origin and biotope

This species comes from the Brazilian Amazon, particularly the Rio Solimões basin and associated floodplain areas. It inhabits slow to moderately calm waters, often along shorelines, flooded forests, and small channels. The habitat generally includes soft water, a fine bottom, and abundant plant material. In an aquarium, this combination can be recreated with fine, non-abrasive substrate, roots, leaf litter, and subdued lighting. Chemical stability is more important than pursuing extreme water values.

Precise location and local name

Geographic records associate Dianema urostriatus/longibarbis with the Rio Solimões basin within the Brazilian Amazonian network. In the aquarium trade, it is mainly identified by its scientific names or by the English name Flagtail Catfish. In Brazil, the generic term “cascudo” may be used for several armored catfish, but it does not exclusively identify this species. To avoid confusion, the scientific name remains the best reference, especially because Dianema urostriatum and Dianema longibarbis have been associated in taxonomic and aquarium usage.

Appearance and physical characteristics

Dianema urostriatus/longibarbis has an elongated, sturdy body protected by two rows of bony plates. The base coloration ranges from grayish beige to light brown, with darker markings. Its most distinctive feature is the darkly patterned tail, which inspired the name Flagtail Catfish. The barbels are long and are used to probe the substrate. The fins are generally translucent to brownish, while the head is flattened, as in several bottom-feeding catfish. Adult size reaches approximately 10 cm, depending on the individual and growing conditions.

General diet

Dianema urostriatus/longibarbis is an omnivore with a detritus-feeding tendency that searches for food along the bottom. Its diet may include insect larvae, small invertebrates, organic debris, and plant matter. In an aquarium, offer quality sinking wafers, catfish pellets, and frozen foods such as mosquito larvae and bloodworms. Feeding after the lights go out helps shy individuals eat without competition. It should not be considered a cleaner fish: a regular, targeted feeding routine is still necessary to prevent competition with midwater fish.

Essential data

• River of origin: Rio Solimões
• Local name used: Cascudo, a generic Brazilian term
• Origin of the scientific name: Dianema urostriatum; longibarbis is an associated taxonomic name
• Full-name etymology: Dianema probably means “two filaments”; urostriatum means “tail-striped”; longibarbis means “long-bearded”
• Common/vernacular names: Flagtail Catfish, striped-tail catfish
• Family: Callichthyidae
• Subfamily: Callichthyinae
• Name pronunciation: dee-ah-NEH-mah oo-roh-stry-AH-toum
• Discovery: Edward Drinker Cope, 1872, for Dianema longibarbis; Alípio de Miranda-Ribeiro, 1912, for Dianema urostriatum
• Maximum adult size: About 10 cm
• Water temperature and pH: 24 to 28 °C; pH 6.0 to 7.5
• Stream appearance and surrounding vegetation: Slow-moving water, wooded banks, flooded areas, roots, and leaf litter
• Typical tankmates: Brochis splendens, Hoplisoma agassizi, Hemigrammus rhodostomus, Pterophyllum scalare
• Temperament and behavior: Peaceful, social, discreet, and mainly active near the bottom
• Water depth: Shallow to moderately deep shoreline areas and channels
• Sexual dimorphism: Females are generally rounder; differences are subtle outside breeding condition
• Bottom structure and flow: Fine sand or mud, plant debris, and low to moderate current

In your aquarium

To keep Dianema urostriatus/longibarbis successfully, use a mature, well-oxygenated aquarium furnished with bottom-level hiding places. Keep it in a small group, choose soft sand, and avoid aggressive or overly competitive tankmates. Stable water, varied sinking foods, and regular water changes are the foundations of success. Since this is a wild-collected species, pay particular attention to acclimation, barbels, and feeding response during the first few weeks.