Black Phantom Tetra

The Black Phantom Tetra is a subtly colored characin native to slow-flowing streams and swamps of the Paraguay and Guapore river basins in Brazil, Bolivia, and Paraguay. Its body is a smoky translucent gray, deepening toward silver-black on the flanks, with a prominent black shoulder blotch shaped like a teardrop that gives the 'phantom' group its name. Males develop dramatically enlarged, sail-like dorsal fins edged in white, contrasting against the darker body and used prominently in territorial and courtship displays. Females are smaller-finned and generally show a more muted overall coloration, making the species one of the more visibly sexually dimorphic tetras commonly kept in aquariums.

• Smoky gray to silver-black translucent body
• Bold, elongated black shoulder blotch behind the gill cover
• Tall, sail-like dorsal fin in males, often white-edged
• Reddish tint sometimes present on pelvic and anal fins
• Females noticeably smaller-finned with duller overall tone
• Slender, laterally compressed characin body shape

The clearest distinction from its close relative, the Red Phantom Tetra, is overall body hue: gray-black rather than pink-red. Males of both phantom species share exaggerated dorsal finnage used in ritual displays, making fin shape a poor standalone identifier without considering base coloration.

Black Phantom Tetras inhabit slow-moving streams, swamps, and flooded forest margins within the Paraguay and Guapore river drainages of central South America, spanning parts of Brazil, Bolivia, and Paraguay. These waters are often softly acidic to neutral, shaded by riparian vegetation, and rich in leaf litter and submerged roots that provide cover and foraging substrate. The species favors calmer backwaters over strong current, shoaling near vegetation and woody debris where visibility is often reduced by tannins or suspended sediment. Its wide native range across multiple river systems has allowed it to remain relatively common and adaptable to varied freshwater conditions within the broader Paraguay-Guapore basin.

Black Phantom Tetras display notable social hierarchy behavior, with males establishing loose dominance through fin-flaring and brief chasing rather than sustained aggression. They form loose, mixed-sex shoals in which dominant males claim small display territories to attract females, spreading their enlarged dorsal fins in stylized posturing. Diet consists of small invertebrates, insect larvae, and plant matter foraged from the substrate and water column. Spawning follows the classic egg-scattering characin pattern, with adhesive eggs deposited among fine vegetation and no parental care afterward. Their moderate activity level and visible social displays make them popular for observing characin courtship dynamics, and larger groups tend to reduce stress-related fin-nipping among males.