Atlantic Blue Tang

Snapshot: As a juvenile, this surgeonfish shines in bright yellow, featuring two striking blue bands at the eyes. As it matures, its blue hues intensify, with horizontal markings spanning the entire body, retaining a hint of yellow in the tail. 
 
Other tidbits: Can grow up to a whopping 39cm or so! Native to the Western Atlantic Ocean. This fish can dial up its color intensity, seemingly reflecting its mood swings.
 
Bare bones must know: Live-rock fish-only system, or reef aquarium. Larger size aquarium needed.