Scientific name: 
Acanthurus olivaceus
Distinctive features: 
1. Orange band on front half of fish 2. Can have light gray to very dark body color 3. Often has distinctive light front half and dark back half 4. Juvenile is yellowish with a dark band showing (that will later turn orange) 5. Tail is straight edged as a juvenile, but grows long trailing edges as adult
Size: 
Up to 12" (30cm)