Pink-tailed Chalceus

Geographic Origin and Biotope: Native to northern South America: Orinoco and Amazon river basins (Guyana, Suriname, Colombia, Peru). Inhabits highly oxygenated crystal-clear rivers and fast-flowing jungle streams, constantly hovering just below the water surface waiting for insects to fall.

Taxonomy and Morphology: Known as the Pink-tailed Chalceus. It is a large characin belonging to the Chalceidae family (related to piranhas but with an insectivorous diet). Slender, hydrodynamic profile, strong upward-facing mouth. The unmistakable feature is the disproportionately gigantic silvery scales (macrolepidotus) covering the upper part of its body.

Social Behavior: Extremely fast and skittish surface predator. Juveniles are gregarious, while as they grow they become extremely hostile toward conspecifics due to surface food competition. They must be kept either as a single specimen or in small groups (at least 5-6) in immense tanks to diffuse deadly hierarchical fights.

Coloration and Sexual Dimorphism: The body is covered by an armor of giant bright silver scales with bluish reflections. The extraordinary contrast is provided by the massive caudal fin (tail) and pelvic fins which take on a neon pink or bright fuchsia coloration. Mature females have a visibly more swollen and arched belly.

Aquarium Setup: Categorical imperative: enormous tank (minimum 150-200 cm / 5-6 feet in length) and a heavy, tightly fitted lid. They are formidable ballistic jumpers that will hit the top glass hundreds of times in their life. The surface area must be completely clear for free swimming, with strong filter output current at the surface.

Diet and Feeding: Surface carnivore and formidable insectivorous hunter. In the wild, it eats large insects, frogs, and small pelagic fish. In the tank, it refuses food that falls to the bottom. Feed with live crickets (gut-loaded), mealworms, earthworms, freeze-dried shrimp (Krill), and floating pellets for large cichlids.

Water Quality: Accustomed to rushing and pristine river waters, it demands extremely high levels of dissolved oxygen and suffers from pollution. The optimal temperature ranges from 23.0 to 28.0 °C (73-82 °F). The ideal pH is slightly acidic to neutral (6.0 - 7.5) in waters of medium to low hardness (GH 5-15).

Compatibility and Tankmates: Does not attack fish residing at the bottom of the tank. Splendid companion for XL South American biotope tanks: coexists perfectly with huge Plecostomus, large Loricariids, Geophagus, Satanoperca, and Oscars. Obviously, it will swallow small Tetras or Corydoras in a single bite.

Aquarium Reproduction: An extremely rare occurrence for home hobbyists. It is assumed they scatter free eggs in the strong current among marginal submerged vegetation during the rainy season. They do not practice parental care. Captive breeders would require thousands of liters of flowing water to trigger the event.

Risks and Diseases: Self-inflicted traumatic injuries. In the early days or due to a sudden movement in front of the tank, they will panic, launching themselves at insane speeds against the glass or lids: lacerations of the snout (which become infected with Columnaris) and loss of eyes are the main cause of death.