One-line Tetra

Geographical Origin and Habitat: Widely distributed across northern South America, including the river basins of Venezuela, Trinidad and Tobago, Guyana, Suriname, French Guiana, and the Amazon River basin in Brazil. It inhabits slow-flowing streams, drainage ditches, temporary pools, and flooded forest areas.

Taxonomy and Morphology: Belongs to the family Characidae and genus Hemigrammus. Scientifically described by Gill in 1858. It features a laterally compressed, fusiform body typical of small characins, reaching a maximum length of about 4.5 to 5.0 cm. Possesses a small adipose fin.

Social Behavior: An extremely peaceful, active, and schooling fish. It lives in tight groups that constantly swim in the middle layers of the water column. Must be kept in groups of at least six to eight individuals to promote schooling behavior, reduce shyness, and display natural activity.

Coloration and Sexual Dimorphism: Body is translucent silvery-grey with golden reflections. It is distinguished by a prominent diagonal black line bordered by white or neon yellow on the anal fin, and a black blotch on the dorsal fin. Males are slimmer and slightly smaller than mature females, which have a rounder abdomen.

Aquarium Setup: Suitable for aquariums of at least 60-80 liters (15-20 gallons) with a minimum length of 60 cm. Provide dense planting along the sides and back (using species like Vallisneria), leaving the central area open for swimming. Add driftwood, roots, and dried leaf litter to mimic natural blackwater.

Diet and Feeding: Omnivorous and easy to feed. Accepts high-quality flakes and micro-pellets. To encourage optimal health and coloration, supplement their diet regularly with live or frozen foods such as daphnia, brine shrimp, and cyclops. Feed once or twice daily.

Water Quality: Very adaptable, but prefers soft, slightly acidic to neutral water. Maintain temperature between 22°C and 28°C (72-82°F), pH 6.0-7.5, and hardness 5-15 dGH. Weekly or bi-weekly water changes of 20% are recommended to keep nitrates low.

Compatibility and Cohabitation: An excellent choice for a peaceful community tank. It can be housed with other small tetras, rasboras, corydoras, peaceful dwarf cichlids (like Apistogramma), and small loricariids. Do not house with large, predatory, or aggressive fish.

Aquarium Breeding: Relatively easy to breed. Egg scatterers that spawn among fine-leafed vegetation (such as Java moss). Spawning requires a separate breeding tank with soft, acidic water, dim lighting, and fine plants. Remove the parents immediately after spawning to protect the eggs.

Risks and Diseases: A hardy species, but vulnerable to ich (white spot disease) if exposed to sudden temperature drops or poor water quality. It responds well to standard commercial anti-parasitic treatments. Ensure proper filtration to avoid organic waste buildup.