Histopathological study of Lipoidosis (fatty change) inrainbow trout farms of West Azerbaijan province

Liver is the main organ in fat metabolism and its ability in storing and metabolism of extra fat available infeedstuff is, in rainbow trout this ability is limited so the extra fat of feedstuff can be piled up in liver and leadto Lipoidosis. In this study 120 rainbow trout from western Azerbaijan’s rainbow trout farms during fall andwinter were randomly selected and put into four different weight groups (below 50-50to150-150to250and above250gr) for the analysis of Lipoidosis disease.after biometric experiments the fshes were autopsied and aftersampling and tissue stabilizing in formaldehyde the pathological sections of 135 samples of suspicious liver wereprepared in 5micrometer diameter and colored by two methods of PAS and H&E (for determining fat).In liversaffected by Lipoidosis the penetration of fat into hepatocyte was seen as clear vacuoles so that after PAS coloringtheir fatty nature was confrmed because they were not colored. The results show that by an increase in weight.(weight group above250gr) the rate of Lipoidosis increase too, the study histopathological sections in affectedlivers other damages like focal Lymphocytosis low to acute bleeding, dilation of central veins and increaseof melanomacrophage focuses as well as Lipoidosis were seen. By noticing the high outbreak of this disease inweight group above 250gr whish has also the probability of economic losses.