Cochlodinium polykrikoides (or Margalefidinium polykrikoides) is a species of red tide producing marine dinoflagellates known for causing fish kills around the world, and well known for fish kills in marine waters of Southeast Asia.

Margalefidinium (formerly Cochlodinium) polykrikoides is the organism responsible for large, dense brown-colored algal blooms known as “rust tide.” These chain-forming dinoflagellates are found along the east coast from Massachusetts to Florida, and the rust tides they produce can stretch for tens to hundreds of kilometers.

Margalefidinium polykrikoides (=Cochlodinium polykrikoides) is a photosynthetic and mixotrophic marine dinoflagellate that forms cysts. It forms harmful algal blooms (HABs), causing economic losses in fish farming areas (US$140M in world wide; Dorantes-Aranda, 2012) mainly in Asia (Kim, 1998; Kim et al., 1999; Zhong and Gobler, 2009).

Margalefidinium polykrikoides (previously known as Cochlodinium polykrikoides) is a toxic dinoflagellate algae found in Chesapeake Bay.

Margalefidinium (previously Cochlodium) polykrikoides. An athecate (i.e., “unarmored”), chain-forming dinoflagellate. Forms small chains of typically 2-8 cells.