Pristella Tetra (Pristella maxillaris)

Pristella maxillaris earns the nickname "X-ray tetra" honestly, the body is translucent enough to make out the swim bladder and internal structure without a dissection, and the dark-tipped fins with a pale spot underneath are thought to function as a warning-coloration mimicry of more toxic species, though that's still debated among ichthyologists. Whatever the evolutionary reasoning, it's one of the hardiest tetras sold, tolerant of a wider water-parameter swing than most of its Amazon relatives. A genuinely good first tetra for a beginner tank.

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