Pacific YBD first appears as a pale yellow blotch within the colony perimeter or as a narrow band at the colony margin. The pale yellow areas are living coral tissue located adjacent to normal, fully pigmeneted brown or greenish tissue. As the band/blotch progresses it typically forms a circular or annular ring separating normal tissue from algal-colonized skeleton. Progression is generally slow, and often white, recently denuded skeleton is absent or limited to small irregular patches consisting of a few polyps.
Pacific yellow band disease (PYBD) is only known to affect Diploastrea heliopora, Fungia spp. and Herpolitha spp.
In Fungia spp., diseased tissue appeared as one or more irregular blotches dispersed over the corallum, often forming an expanding circle, but not the circular rings seen in faviids. In advanced stages, the yellow lesions in Fungia disappear as host tissue is degraded, and a pink coloration becomes evident in the skeleton.