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The Platystacus cotylephorus, also known as the Eel-Tail Banjo Catfish, is a South American catfish with a highly distinctive profile. Its flattened body, broad snout, and very elongated tail create an immediately recognizable shape adapted to life on the bottom. Native to coastal waters of Brazil, it inhabits quiet areas where soft substrate allows it to remain inconspicuous. This wild-collected species remains very rare in the aquarium trade and is offered exclusively by Ton.Fish in Canada. Its peaceful, mainly nocturnal behavior appeals to aquarists looking for an unusual bottom-dwelling fish.

General description

The Platystacus cotylephorus belongs to the banjo catfish group, recognized by flattened bodies and adaptations for benthic life. It generally rests on the bottom during the day and becomes more active as the light fades. Its subdued appearance provides effective camouflage among mud, dark sand, leaf litter, and submerged roots. In an aquarium, it benefits from a mature, calm, well-oxygenated setup with plenty of cover close to the substrate. Despite its unusual appearance, it is generally peaceful with similarly sized tank mates. Because it is a very rare, wild-collected species, acclimation deserves special attention: gentle transport, stable water, and food available after dark.

Geographic origin and biotope

The Platystacus cotylephorus is associated with Brazil, especially lowland coastal and estuarine aquatic environments in the northern part of the country. It inhabits slow-moving or nearly still water, sometimes affected by tides, where the bottom consists of mud or fine sand. Riparian vegetation and woody debris create shaded areas, while leaf litter and roots provide shelter close to the substrate. These habitats may have water tinted by organic matter and variable mineral content. In an aquarium, the main goal is to reproduce the quiet conditions of the natural environment, with little turbulence and plenty of covered surfaces. Efficient filtration without excessive bottom current is more suitable for its lifestyle than a strongly flowing layout.

Specific location and local name

The known range of the Platystacus cotylephorus lies in low-lying coastal areas of Brazil, associated with fresh to slightly brackish waters. In the aquarium trade, it is commonly called the Eel-Tail Banjo Catfish. In Portuguese, bagre-banjo is used for banjo catfish. Its presence in coastal habitats explains why some natural environments may experience slight salinity influence, although stable freshwater remains the most practical approach in captivity. Because commercial information on this very rare species is limited, scientific identification should be prioritized, especially when purchasing a wild specimen.

Appearance and physical characteristics

The Platystacus cotylephorus has a flattened shape, a broad head, and a body covered with bony plates typical of banjo catfish. Its most striking feature is its very elongated caudal peduncle, which gives the tail an eel-like appearance and explains the name Eel-Tail Banjo Catfish. The coloration is generally brown to grayish brown, with irregular shades that blend into the substrate. The eyes are small, the snout is adapted for locating food on the bottom, and the pectoral fins have reinforced rays. This combination of a flattened form, cryptic coloration, and threadlike tail helps it remain hidden among debris and mud. The reported maximum adult size is approximately 15 cm.

General diet

The Platystacus cotylephorus searches for food on the bottom, particularly as the light level decreases. Its natural diet includes small benthic organisms such as worms, insect larvae, and small crustaceans. In an aquarium, food should be placed close to the substrate so it remains accessible after the lights go out. Protein-rich sinking tablets, bottom-feeder pellets, and frozen foods such as bloodworms or brine shrimp can be offered in rotation. Meals should remain moderate because food buried in mud can quickly affect water quality. Feeding at dusk better matches its nocturnal behavior. With a wild and very rare specimen, monitoring feeding activity is essential during the first few weeks.

Essential data

• Native river name: Coastal and estuarine Brazil
• Local name used: Bagre-banjo
• Origin of the scientific name: A generic name combined with a descriptive specific epithet
• Etymology of the full name: Platystacus comes from Greek and refers to a flattened form; cotylephorus means cup-bearing or sucker-bearing, referring to a cup-shaped structure
• Common/vernacular names: Eel-Tail Banjo Catfish; Eel-tail banjo catfish; bagre-banjo
• Family: Aspredinidae
• Subfamily: Aspredininae
• Name pronunciation: pla-tis-TA-kus - kot-yl-ee-FOR-us
• Discovery: Franz Steindachner, 1876
• Maximum adult size: Approximately 15 cm
• Water temperature and pH: Approximately 24 to 28 °C; pH around 6.0 to 7.5
• Watercourse appearance and surrounding vegetation: Slow coastal waters with shade, mud, leaf litter, roots, and riparian vegetation
• Typical tank mates: Peaceful small characins, calm small cichlids, Corydoras, small loricariids, adult shrimp, and other non-aggressive bottom fish
• Temperament and behavior: Peaceful, secretive, mainly nocturnal, and benthic
• Water depth: Shallow to moderately deep areas close to the substrate
• Sexual dimorphism: Limited and difficult to identify with certainty
• Bottom structure and flow: Mud or fine sand, organic debris, and low current

In your aquarium

Success with the Platystacus cotylephorus depends on a mature, peaceful aquarium designed around the bottom. Use fine, non-abrasive substrate, roots, leaf litter, and low shelters to reduce stress. Maintain stable water, good oxygenation, and moderate flow while offering food in the evening. Avoid aggressive or highly competitive tank mates. Since this species is very rare, wild-collected, and exclusive to Ton.Fish in Canada, slow acclimation and close observation are especially important.