Answer:
I think that Julia's perception of the trout is a sensation of pity for it.
Step-by-step explanation:
After reading this excerpt, we can understand that Julia feels relieved when she sees the trout. She stops being so afraid when she sees the trout in what she perceives as a prison. She feels kind of sorry for the trout. She feels sad for it and for the darkness it lives in, and that makes her own fear feel smaller.