Stony coral tissue loss disease (SCTLD) is a disease of corals that first appeared off the southeast coast of Florida in 2014. It originally was described as white plague disease.[1] By 2019 it had spread along the Florida Keys and had appeared elsewhere in the Caribbean Sea. The disease destroys the soft tissue of at least 22 species of reef-building corals,[2] killing them within weeks or months of becoming infected. The causal agent is unknown but is suspected to be either a bacterium or a virus with a bacterium playing a secondary role. The degree of susceptibility of a coral, the symptoms, and the rate of progression of the disease vary between species.[3] Due to its rapid spread, high mortality rate, and lack of subsidence, it has been regarded as the deadliest coral disease ever recorded, with wide-ranging implications for the biodiversity of Caribbean coral reefs.[4]