Orchid Dottyback

Snapshot: Orchid Dottybacks dazzle with their vibrant purple bodies and fins, some flaunting red fringes on the top and bottom. A distinctive black stripe runs from their mouth through their eye.
 
Other tidbits: Can grow up to 7cm or so. Native to the Red Sea.
 
Bare bones must know: Live-rock fish-only system, or reef aquarium. Known for preying on pests like small mantis shrimp and bristleworms, it's a top choice for reef aquariums.