Tissue necrosis is when a coral loses its skin/flesh which results in exposed coral skeleton or coral melting. Coral bleaching is when the coral loses its zooxanthellae causing the coral skin to turn white. There are two kinds of tissue necrosis, Rapid Tissue Necrosis (RTN) and Slow Tissue Necrosis (STN). Rapid Tissue Necrosis can occur in the matter of hours, usually within 24 hours. Slow Tissue Necrosis can take days to months. Both coral RTN and STN are caused by an infection of the coral tissue and skeleton by microscopic protozoans. These protozoans are a family of single cell microscopic organisms with cilia that are found both in the water column and within the coral tissue and skeleton. In 2018, Dr. Ara Deukmedjian performed a series of tests at Prime Coral Labs proving these protozoans are the cause of coral dieases RTN and STN by culturing and infecting coral samples with the protozoans. Because colonization of a healthy coral by the protozoans ultimately and ALWAYS leads to coral disease (RTN, STN and bleaching) and death, we must classify these protozoans as parasites. The parasites do not benefit the coral in any way and always cause coral tissue necrosis by consuming the coral tissue along with its zooxanthellae. These parasites cannot be seen with the naked eye or a magnifying glass. They can only been seen under a light microscope. Findings All corals demonstrating rapid tissue necrosis were infected with an infestation of philaster lucinda and philaster guamense without exception. RTN’ing coral typically had approximately 500 to 1000 individual philaster per cubic centimeter of infected coral tissue (including the skeleton) in the RTN zone. Corals experiencing slow tissue necrosis (STN) were infected with a varity of non-philaster ciliated protozoans including Euplotes, Dysteria, Cryptocrayon, Varistrombidium, and Litonotus. These RTN and STN parasites were found in large numbers consuming coral tissue and zooxanthella in ALL corals with tissue loss typically seen in diseases commonly referred to as white band syndrome, white patch syndrome, white plague, brown jelly, and coral bleaching. Healthy corals did not have the RTN or STN parasites present in their tissue under microscopic examination. Healthy coral fragments were placed in isolation and allowed to die. After the corals expired, none of the RTN or STN parasites were found on the coral or in the water column. RTN or STN parasites were only found in diseased corals with tissue loss. RTN and STN parasites were isolated from diseased corals and cultured. Normal healthy coral was exposed in isolation to the RTN and STN parasites. After several days the healthy corals began to show signs of infection and disease with the RTN and STN parasites. Bleaching and tissue loss on coral branches occurred that was consistent with RTN and STN previously described. RTN and STN parasites were isolated from the newly infected and diseased (previously healthy) corals. Histologically they were identical to the ciliated protozoans that were isolated from corals demonstrating spontaneous tissue necrosis. These experiments utilize Koch’s Postulates to prove a causal relationship between the ciliated protozoans (RTN and STN parasites) and coral tissue necrosis.