Glowlight Tetra (Hemigrammus erythrozonus)

Hemigrammus erythrozonus has been in the hobby since the early 1920s, and that orange stripe running the body length comes from refractive iridocytes reflecting light back at a narrower band than the ones behind neon tetra blue, a different structural trick aimed at the same glowing effect. Guyana blackwater is its native range, tannin-stained and dim, exactly the low-light conditions that make a reflective stripe worth having in the first place. One of the easiest, most forgiving schoolers you can build a first tank around.

Care level: Easy · Temperament: Peaceful, shoaling · Max size: ~1.5" · Min tank: 15 gal · Diet: Omnivore, flake/micro-pellet