Cestodes (tapeworms)

Cestodes (commonly known as tapeworms) are flat, segmented worms in Phylum Platyhelminthes, Class Cestoda. They have complex life cycles that involve three hosts: the first intermediate host is a copepods, the second intermediate host is a fish, and the final host is a fish-eating bird, mammal or other fish. In fish, juvenile cestode stages (metacestodes) are found in internal organs or muscle, with the adult stages in the intestine. Cestodes rarely cause high mortality but may retard growth, and lead to adhesions that impair host metabolism and reduce fecundity.