Black Skirt Tetra

The Black Skirt Tetra is a small characin native to the Paraguay, Guaporé, and Rio Negro river basins of South America. A member of the family Characidae, it is one of the most recognizable tetras due to its dramatic black, skirt-like anal and tail fins. Wild populations remain common and the species faces no significant conservation concern. In its native rivers it is part of a diverse assemblage of small schooling characins occupying quiet, vegetated waters. The species' bold coloration and easy adaptability have made it a long-standing staple of freshwater fishkeeping since the early 20th century.

Key field marks:

• Diamond-shaped, laterally compressed body, silvery-gray at the front
• Body darkens toward the rear into smoky black or charcoal shading
• Tall, flowing black anal fin extending in a skirt-like sweep
• Two faint vertical dark bars crossing the body just behind the head
• Forked tail often edged in black or dark gray
• Adults reach about 4.5-6 cm Juveniles show the most intense black coloration, which typically fades to a paler gray as the fish ages, a useful clue for estimating relative age.

Black Skirt Tetras inhabit slow-flowing rivers, tributary streams, and quiet backwaters within the Paraguay River basin and adjacent drainages of Brazil, Bolivia, and Argentina. They favor soft, slightly acidic to neutral water with abundant aquatic vegetation and submerged structure for cover. Native water temperatures generally range from 20-26°C, reflecting a subtropical climate somewhat cooler than many Amazonian tetras. They are typically found in shallow marginal habitats with moderate to low flow, where fine sediment and plant growth support the small invertebrates they feed on.

Black Skirt Tetras are active, hardy shoaling fish that move together in loose groups through open water and around vegetation, feeding on small invertebrates, insect larvae, and plant matter. They are known to nip at the fins of slow-moving or long-finned tankmates, a behavior more pronounced in small groups. Spawning is an egg-scattering process performed among fine plants with no parental care, and eggs hatch within about a day in warm water. Their schooling behavior offers protection from predators, while their omnivorous foraging helps control small invertebrate populations in their native streams.