Congo Tetra (Phenacogrammus interruptus)

Phenacogrammus interruptus gets that shifting rainbow sheen from the same structural iridophore layer responsible for neon tetra color, just scaled up across a much bigger body, and mature males grow trailing extensions off the dorsal and caudal fins that females never develop. It's one of the larger tetras in the trade and needs real swimming room to look and behave its best. A proper school under decent lighting is genuinely one of the more striking sights in freshwater.

Care level: Easy · Temperament: Peaceful, shoaling · Max size: ~3.5" · Min tank: 30 gal · Diet: Omnivore, flake/pellet