Blue or Yellow Assessor Basslet

Snapshot: Dressed in dusky dark blue from head to tail, this fish is a top pick for reef aquariums.
 
Other tidbits: Can grow up to 7cm. Native to the outer barrier reefs of Australia and spreading across the Coral Sea, this species also calls the reefs of Papua New Guinea and New Caledonia home.
 
Bare bones must know: Live-rock fish-only system, fish-only system, or reef aquarium.