Green Fire Tetra (Aphyocharax rathbuni)

Aphyocharax rathbuni carries two iridophore layers running slightly out of phase with each other, which is why the flank flashes green from one angle and red from another rather than settling on a single fixed color the way most tetras do. It's a genuinely active, quick-moving fish out of the Paraguay and Bolivia river basins, built more for open water than dense cover. A tight school under good lighting turns that two-tone flash into a moving light show.

Care level: Easy · Temperament: Peaceful, shoaling · Max size: ~1.75" · Min tank: 15 gal · Diet: Omnivore, flake/micro-pellet