The short-term aggressive behavior of scleractinian corals from La Blanquilla Reef, Veracruz Reef System, Gulf of Mexico was determined. Unilateral aggression, bilateral aggression and indifference were observed through experimental interspecific encounters in situ, in aquarium conditions and through direct observation of natural encounters on the reef. Species were characterized as highly aggressive, moderately aggressive and not very aggressive establishing a hierarchy with two competitive rings representing similar aggressive abilities among some species. Most observations of aggression were of extracoelenteric digestion. Mussa angulosa was the most aggressive species and Oculina diffusa the least. Apparently there is a direct relationship among aggressiveness and relative coverage as three of the most abundant corals at dephts of 4-9 m Montastraea cavernosa, Colpophyllia natans and Montastraea annularis, are all highly aggressive, have massive growth and have a high relative coverage. Siderastrea siderea is the only dominant species that was not ranked as highly aggressive; its high coverage is due to other reasons.
Keywords: scleractinian, coral, aggression, behavior, veracruz