The Blue Flash Glass Tetra, scientifically known as Heterocharax virgulatus, is a rare and striking tetra native to the blackwater and clearwater tributaries of the Amazon and Orinoco River basins in South America. It is admired for its iridescent blue flash along the body and delicate, glasslike appearance.

Adult Blue Flash Glass Tetras typically grow to about 1.5 to 2 inches (4 to 5 cm) in length. They have a slender, translucent body that shimmers under light, with a distinct electric-blue line running laterally from behind the gill cover to the caudal peduncle. Under aquarium lighting, the reflective blue and green hues shift as they move, giving them a constantly changing “flash.” The fins are generally clear with a faint yellow or rose tint.

A tank of at least 20 gallons is suitable for a school. Blue Flash Glass Tetras are a true schooling species, and a group of five or more individuals is highly recommended to ensure security, natural behavior, and display of full coloration. The aquarium should include a fine sand substrate, driftwood, roots, and dense planting, leaving open space for swimming. Floating plants or dim lighting help bring out their iridescence.

Water parameters should include a temperature of 74 to 80°F (23 to 27°C), a pH between 5.5 and 7.0, and soft to moderately soft water. They thrive in clean, well-oxygenated water with regular partial changes and gentle but steady filtration. These fish have been observed to behave best in aquariums with moderate to high water flow, which helps replicate the moving currents of their natural habitat and keeps them active and comfortable.

Feeding Heterocharax virgulatus is straightforward. They are micro-predators and accept small foods such as micro pellets, crushed flakes, and live or frozen fare like daphnia, cyclops, or baby brine shrimp. A varied diet enhances their health and intensifies their color.

Blue Flash Glass Tetras are peaceful and ideal for community aquariums with other small, calm fish such as pencilfish, rasboras, Corydoras, or Apistogramma. Avoid housing them with large or aggressive tankmates that might intimidate them.

Breeding is rare and not well documented in captivity. They are likely egg scatterers with no parental care, depositing eggs among fine plants or leaf litter. If spawning occurs, eggs should be protected from adults to ensure survival.

Heterocharax virgulatus (Blue Flash Glass Tetra) is a graceful and luminous species that adds motion, rarity, and shimmer to blackwater and planted aquariums. When kept in groups and provided with lively water movement, they exhibit their most vibrant coloration and natural schooling displays.