AYB manifests as a bright yellow band of one to several cm in diameter at the interface of healthy and dead coral.
The band migrates across the coral in a linear to annular pattern, producing a margin of decaying tissue adjacent to healthy tissue. As the band progresses, dead skeleton may retain a yellow pigmentation, or it becomes greenly discolored in the genus Porites or, in Acropora, is usually pure white.
The yellow band is raised above the surrounding tissue and appears often to have a thin mucous envelope. Unlike BBD, no filaments or microbial band are visible.