Genicanthus lamarck adults are pale greyish to whitish in colour marked with 4-5 irregular black undulating stripes which radiate out from the eye and run horizontally along the flanks.

[2] Genicanthus lamarck is found from the Gulf of Thailand east through the Malayan Archipelago to the Solomon Islands, north as far as southern Japan and south to the Great Barrier Reef.

[1] Its Australian distribution also includes Ashmore Reef and Cartier Island in the Timor Sea.

[1] It is found in areas of dense coral growth on the seaward slopes of reefs and on steep drop-offs.

[3] Genicanthus lamarck was first formally described in 1860 as Holocanthus caudovittatus by the French naturalist Bernard Germain de Lacépède (1756-1825) with no type locality given.