The presence of oil/fat vacuole in the livers of rainbow trout depends primarily on the type of diet they receive during the course of experimentation . Following article might help you in this regard.

http://www.ncbi.nlm.nih.gov/pubmed/6445002

The vili is definitely showing presence of fat vacuole but they are absent in the first image 

Thank you for your answer. Four isonitrogenous (45% crude protein), isoenergetic (17.45 MJ/kg) diets and fish meal protein replaced by DDGS protein for 84 days. The objective of this study is to evaluate the effects of replacing FM protein with DDGS protein on liver and intestine histology. Is this where the fat droplets shown with arrows in the villi picture? In another liver picture Is this where the fat droplets shown with arrows in the liver cells. can we say there is mild fat accumulation in liver of rainbow trout

I have some doubts about fat accumulation in the second image but the first image rightly shows the accumulation of fat 

• First I want to thank you for your reply. Are you sure fat accumulation dots in villi. Are dots vesicle for endocytosis - pinocytosis?

In histological sections through the intestine image, can be observed some goblet cells (large white dots). Other dots (smaller) are vesicle for endocytosis - pinocytosis.

• https://www.researchgate.net/post/Does_anyone_have_knowledge_about_fish_liver_and_intestine_histology