Studies on Visceral Mycosis of Salmonid Fry—I

Histopathology

Abstract

Histopathological observation was made on 20 diseased rainbow trout fry and 5 amago salmon fry (O. rhodurus f. macrostomus).
1) Saprolegnia diclina infection: Fungal hyphae grew in the lumen of the pyloric region of the stomach. Hyphae extended from the gastric epithelium into the muscle layers in which they grew markedly. Further hyphae extended out from the stomach wall into the pancreas, pyloric caecae, spleen, abdominal cavity, abdominal musculature and visceral blood vessels in which hyphal emboli were formed frequently.
2) Infection with an unidentified fungus which had thin septate hyphae: Fungal hyphae markedly grew in the swim bladder. They invaded the wall of the anterior region of the swim bladder and extended into the liver, gall bladder, kidney, wall of the esophagus and the cardiac region of the stomach, body musculature and into the visceral blood vessels.