Long-Fin Neon Tetra (Paracheirodon innesi)

Take the same structural-color blue stripe that makes a standard neon tetra glow under aquarium light, and pair it with a long-fin mutation that trails the dorsal and caudal fins well past where they'd normally stop. The extra fin surface makes them a touch slower, so keep tankmates equally mellow. Shoal them tight and that iridescent stripe reads as one continuous ribbon of color moving through the group.

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