Chili Rasbora (Boraras brigittae)

The Chili Rasbora is one of the smallest true fish you'll find in the freshwater hobby, topping out at well under an inch, which makes it easy to underestimate until you see a proper school of them lit up in a planted tank. That deep red coloring intensifies with good water quality and a darker substrate, and a group of fifteen or twenty moving together reads less like individual fish and more like a single shifting cloud of color. Despite the delicate look, they're genuinely hardy once established, though their tiny mouths mean tankmates need to be equally small and peaceful — anything that treats a Chili Rasbora as a snack, will.