Reed tetra

Geographic Origin and Biotope: Rio Paraguay (Pantanal area). Lives in marshy lagoons with very shallow waters, suffocated by water lilies and submerged meadows, with no flow.

Taxonomy and Morphology: Dwarf Blue Tetra / False Dawn Tetra (Hyphessobrycon elachys). Tiny cyprinid (Nano-fish). Often confused with Aphyocharax rathbuni (much more robust). Very slender fry-like body.

Social Behavior: Quiet, shy and absolutely gregarious (Schools of 10-15 elements). Males challenge each other by excessively widening their small anal and dorsal fins (Jerky dancers).

Coloration and Sexual Dimorphism: Silvery livery with incredible "metallic blue-purple" shades when hit by light, with an oblong black spot at the base of the tail and pointed anal and dorsal fin (males only). Females are bare.

Aquarium Setup: Tank for Nano-Fish (50-60 cm / 20-24 inches). Bottom of leaves (Catappa/Oak), intricate twigs, ultra-shielded light from floating plants (Limnobium or Pistia). Without surface cover they panic and hide.

Diet and Feeding: Pure micro-predators. Very high quality freeze-dried or powdered feeds. The ideal are cyclops and microworms; if fed large flakes they simply will not eat (mouth too small).

Water Quality: Extremely sensitive to pollutant peaks. Pantanal water requires slight seasonal thermal fluctuations (22°C / 72°F in winter, 26°C / 79°F in summer). They need very gentle filtration without powerful water jets.

Compatibility and Tankmates: Corydoras hastatus (same colors) lives in nature in mixed flocks with H. elachys (Batesian mimicry): putting them together is mandatory for a perfect biotope. Also excellent with Neocaridinas (they do not touch the young).

Aquarium Reproduction: Very elusive. They hide microscopic transparent eggs on moss threads or weak roots. Without ready infusoria (paramecia) the brood of microscopic fry starves to death in 48 hours.

Risks and Diseases: Predation! Their size (2 cm / 0.8 inches and thin body) makes them an irresistible "spaghetti" even for 5 cm (2 inch) fish. They risk being decimated by Bettas and even by large Platies.