Rummy-nose Tetra

The Rummy-nose Tetra is a small, brightly marked freshwater fish native to clearwater tributaries of the Amazon basin, particularly in Brazil and neighboring countries. Its most recognizable feature is the vivid red-orange coloration covering the head, which contrasts sharply with its silvery translucent body and gives the species its common name. The tail fin carries a bold, high-contrast pattern of black and white horizontal stripes, adding to its striking appearance. Highly social, Rummy-nose Tetras form tight, coordinated schools in the wild, a behavior that also makes them a favorite in planted aquariums, where large groups display synchronized swimming. The intensity of the fish's red coloration is often considered an indicator of good health and water quality.

• Bright red-orange coloration covering the head and gill area
• Silvery, translucent body with a slender, torpedo-like shape
• Tail fin marked with three bold black-and-white horizontal stripes
• Forked caudal fin
• Small adipose fin present
• Similar species: False Rummy-nose Tetra (Petitella georgiae) and Brilliant Rummy-nose Tetra (Hemigrammus bleheri) look nearly identical, distinguished mainly by the extent of red coloration and precise tail striping pattern.

Rummy-nose Tetras are native to clear, slow-flowing tributaries and blackwater streams of the Amazon basin, particularly in the Rio Madeira and Rio Negro drainages of Brazil. They favor soft, slightly acidic water with abundant submerged vegetation, roots, and leaf litter, which offers cover from predators and structure for schooling. As a species sensitive to water quality, they are typically found in relatively clean, well-vegetated stretches of forest stream rather than turbid or degraded waterways.

Rummy-nose Tetras are highly social schooling fish, forming large, tightly coordinated groups that move together with remarkable synchronization, a behavior thought to reduce individual predation risk by confusing predators. They feed on small insects, zooplankton, and other tiny invertebrates picked from the water column and among vegetation. Schooling cohesion tends to improve in larger groups, and individuals kept alone or in small numbers typically show more skittish, less confident behavior. Breeding in the wild involves scattering adhesive eggs among fine-leaved vegetation, with no parental care after spawning; the vivid red head coloration can fade under stress or poor water conditions, making it a commonly used indicator of the fish's well-being.