Hyphessobrycon elachys (Weitzman 1984).
Paraguay river drainage in Argentina, Brazil and Paraguay.
This readily eats all manner of dried, frozen and live food.
Best in soft, acidic water, although, like many other small tetras, it can be gradually acclimatised to harder water. Temperature should ideally be around 24-27°C/75-81°F and pH around 6-7.2.
A peaceful tetra suitable for the community tank when in a small group. Provide open spaces and ample submerged vegetation.
Only Hyphessobrycon heliacus from the Tapajós river drainage in Brazil has the combination of elongate dorsal and pelvic fins in mature males. The presence of a large conspicuous black spot on the caudal peduncle is shared with H. elachys.
These two characteristics are not found together in other members of the genus.
Hyphessobrycon elachys differs from H. heliacus in having a silvery, as opposed to golden, colour in life, a broad anal-fin lobe in mature males (vs. absence) and lacking transverse chevron-shaped bars on the sides of the body (vs. presence).
Hyphessobrycon loweae from the Xingu river drainage in Brazil, is another similar species, but again has a golden colour in life and lacks the anal fin lobe in mature males.