Bloodfin Tetra

The Bloodfin Tetra is a small characin belonging to the tetra family, named for its striking blood-red fins that contrast against a silvery body. It is native to slow-moving rivers and tributaries of the Paraguay-Paraná river system in Argentina, Paraguay, and southern Brazil. Long a staple of the aquarium trade, it is valued for its hardiness, tolerance of a wide temperature range, and peaceful schooling nature. Unlike many tropical characins, it can withstand cooler subtropical conditions found in its native southern range. It remains widespread and abundant, with no significant conservation concerns, and continues to be one of the most commonly kept community tetras worldwide.

The Bloodfin Tetra has a slender, laterally compressed, torpedo-shaped body typical of characins, reaching about 4-5.5 cm.

• Body: Silvery-white to pale translucent, with a faint lateral sheen
• Fins: All fins, especially the dorsal, anal, pelvic and forked caudal, are bright red to orange-red
• Eyes: Large and dark, proportionally large for the head
• Shape: Streamlined and slightly compressed laterally

It is distinguished from similar silver tetras by the near-total red coloration of its fins rather than just the tail, and lacks the dark body spots or stripes seen in relatives like the black tetra.

Bloodfin Tetras inhabit slow-flowing rivers, streams, and floodplain pools throughout the Paraguay-Paraná basin of Argentina, Paraguay, and southern Brazil. They favor open water with moderate to low current, often schooling near the surface or mid-water column above soft substrates. Water in their native range tends to be soft to moderately hard and neutral to slightly acidic, with temperatures fluctuating seasonally from cool subtropical winters to warm summers, giving the species unusual tolerance for temperature swings compared to typical Amazonian tetras. They are found in both clear and turbid waters, frequently among submerged vegetation and root tangles that offer cover from predators while still allowing them to forage in open areas.

Bloodfin Tetras are peaceful, highly social fish that form loose, active shoals, moving constantly through open water in search of food. They are omnivorous, feeding on small aquatic invertebrates, insect larvae, algae, and organic debris drifting in the current. As egg-scattering spawners, they release adhesive eggs among fine-leaved plants or debris with no parental care afterward, and eggs are prone to predation by adults if not separated. They are known for their tendency to leap when startled, an adaptation useful for evading predators in shallow water. Schooling behavior provides protection from larger predatory fish and is strongest when kept in groups of six or more.