Abstract
Nutritional myopathy occurred in yellowtail (Seriola quinqueradiata) reared with raw food fish which were rancid during stock with a freezer in Amami Ooshima Island in the winter of 1973. The diseased fish manifested extremely slender bodies and jelly-like muscles. The striated muscle fibers histopathologically underwent various alterations; simple atrophy, clowdy swelling, vacuolar degeneration, atrophy accompanying separation of a salcoplasmic mass and necrosis without an invasion of microorganism, regeneration of muscle fibers and inflammatory responses. The alterations of muscle fibers caused mascular atrophy and compensative production of the interstitial adipose tissue. A lot of masses of macrophages phagocytizing ceroid were formed around arteriolae in the adipose tissue. The muscular atrophy involved the red musculature in the mild case and both the red and white musculature were atrophied in the advanced case. In both cases a lot of masses composed of macrophages phagocytizing ceroid, lipoprotein, hemosiderin and melanin appeared in the liver, the spleen and the renal hematopoietic tissue.
