Luetken's Tetra

Geographic Origin and Biotope: Widely distributed in the Paraná and Paraguay river basins and coastal rivers of southern Brazil and Uruguay. Inhabits rocky streams, lagoons, and ponds in sub-tropical or temperate climates, facing major seasonal thermal shifts.

Taxonomy and Morphology: Hyphessobrycon luetkenii. Among the giants of the genus (reaches 7 cm / 2.8 inches). Corpulent, barrel-shaped or elongated disc-shaped, similar in physiognomy to the Buenos Aires Tetra (H. anisitsi), very muscular and robust.

Social Behavior: Hyperactive and gregarious fish. Its size and frenetic swimming can intimidate quiet fish. Absolutely to be kept in a large school (at least 8) to vent the incessant intraspecific hierarchical skirmishes.

Coloration and Sexual Dimorphism: Silvery coloration and very large, almost mesh-like scales. The anal, caudal, and pelvic fins display a color from pale orange to rusty red. Females are noticeably more pot-bellied and taller than males.

Aquarium Setup: Needs large and spacious aquariums (100+ cm / 40+ inches). Being omnivorous and destructive, it can eat soft-leaved plants: decorate with smooth rocks, mighty wood, Anubias, and Java Ferns. Strong water movement appreciated.

Diet and Feeding: Extremely voracious. Accepts everything: complete pellet foods, flakes, live food. It is essential to provide a large supply of plant matter (blanched spinach, zucchini, spirulina-based flakes) to satiate it.

Water Quality: "Teflon" fish, tolerates everything. Sub-tropical (cool) water species: ideal between 18°C and 24°C (64-75°F), never above 26°C (79°F) for long. pH between 6.0 and 7.5, tolerates moderately hard waters without problems.

Compatibility and Tankmates: Never pair with shy or slow fish. Perfect for "unheated tanks" with other temperate fish: Corydoras paleatus, Gymnocorymbus ternetzi (Black Skirt Tetra), or large peaceful hardy Cichlids.

Aquarium Reproduction: Prolific. Pairs, if fed abundantly, scatter hundreds of transparent eggs among bushes (or fake spawning plants). They are the worst predators of their offspring and must be moved instantly.

Risks and Diseases: Exceptionally long-lived and healthy. The only serious risk is keeping it constantly at 28-30°C (82-86°F): thermal stress will accelerate its metabolism to the point of exhaustion.