Marbled Whiptail

The largest recorded adults reach just over 26 cm, though most are around 18 cm long. The body is stout and sturdy, tapering into an elongated, slender caudal peduncle. Large triangular fins are a distinctive feature. Coloration and patterning vary with the fish's origin and habitat conditions. Fish from still, turbid waters tend to be darker, while those from fast rivers with clear water and sandy substrates are usually lighter.

The marbled whiptail inhabits the Amazon, Orinoco and La Plata river basins across Venezuela, Ecuador, Peru, Brazil, Paraguay and Argentina. In the wild it lives in rivers and tributaries with varying current and water composition, from soft acidic to moderately hard alkaline. It prefers sandy-bottomed areas where it can hide among driftwood and rocks.

This catfish has a peaceful, even shy temperament. It cannot compete effectively with other fish for food or territory. Small fish that inhabit the middle and upper water columns make ideal tank mates. Other catfish, such as corydoras, are good companions on the bottom.

Given its low activity level, a pair of marbled whiptails needs a tank of at least 70–80 L. The aquarium can be decorated in any style, but must have plenty of hiding places. This species prefers soft sandy substrate with natural décor elements: driftwood, stones, boulders, and various artificial ornaments. Long-term health requires stable water chemistry. The fish adapts to a wide range of pH and water dH, allowing it to coexist with other species with different needs.

The marbled whiptail is omnivorous and readily accepts common aquarium foods in captivity: flakes, pellets, tablets, and live, fresh or frozen foods such as chironomid larvae, daphnia and brine shrimp.

Breeding is possible in the aquarium but occurs irregularly. A small group of fish is recommended to allow them to form a pair naturally. During spawning, the male cares for the clutch, carrying the eggs on his lower lip. Fry are highly sensitive to water quality and require frequent feeding; they tolerate starvation poorly.

Like other armoured catfishes, the marbled whiptail has sensitive, scaleless skin vulnerable to harsh chemicals and sudden water parameter changes. Health problems most often result from poor sanitation, leading to bacterial and fungal infections. Key risk factors and preventive measures include: — maintaining high water quality with low nitrate and ammonia levels, since organic buildup quickly causes fin erosion and skin damage; — avoiding medications containing copper, to which this species is highly sensitive; — providing clean sandy substrate without sharp particles that can cause mechanical injuries and secondary infections. A varied diet is important: nutritional deficiencies and monotonous feeding weaken immunity and increase susceptibility to parasites. If signs of illness appear—such as body coating, behaviour changes or loss of appetite—test the water parameters and perform regular partial water changes with fresh, aged water.

When selecting fish, check the skin and fins for integrity: they should be unblemished, with no visible damage, ulcers or white coating. Healthy fish actively search for food on the bottom and should not appear wasted. Avoid specimens with sunken bellies, as this often indicates digestive problems or prolonged stress during transport.