Pfiesteria piscicida: A dinoflagellate with a life cycle that includes numerous flagellated, amoeboid, and encysted stages. Both the flagellated and amoeboid forms produce toxins which cause open wounds on fish. Pfiesteria piscicida feeds on tissue sloughed from these wounds, as well as on bacteria and algae. It is found in Atlantic estuaries of the United States.Protozoan Infections: Infections with unicellular organisms formerly members of the subkingdom Protozoa.Killifishes: Small oviparous fishes in the family Cyprinodontidae, usually striped or barred black. They are much used in mosquito control.Dinoflagellida: Flagellate EUKARYOTES, found mainly in the oceans. They are characterized by the presence of transverse and longitudinal flagella which propel the organisms in a rotating manner through the water. Dinoflagellida were formerly members of the class Phytomastigophorea under the old five kingdom paradigm.Photobacterium: A genus of gram-negative, facultatively anaerobic, rod-shaped bacteria that are common in the marine environment and on the surfaces and in the intestinal contents of marine animals. Some species are bioluminescent and are found as symbionts in specialized luminous organs of fish.