The book and the review in this site’s book reviews of William Faulkner As I Lay Dying include an interesting comment from Vardaman, one of Addie's five children, when he says after she dies that he believes “his mother is a fish.”
Addie’s coffin had been floating down the river, and it reminded him of an encounter with a dead fish earlier in his life. Vardaman had caught just a fish and cut it up into little pieces, noting that once it was cut up, it was evident that it was no longer a fish.
Even with this background, Vardaman's comment, “My Mother is a fish,”*stands out as odd, so we may ask ourselves why Faulkner had Vardaman say this.
It may be conciseness taken to a new level, cutting unnecessary words while conveying an idea, enhancing communication by eliminating redundancy.
Was it meant to be profound, symbolic, or show a poor understanding of death? Maybe it was religious, intending to show that mom was no longer in the box, but fish would be soon? Most likely, it was just a poor understanding of what death was.
The fish was previously caught and was a fish; then it was cut up and was not a fish. Or, as Vardaman sees it and says, it was a fish, and now it’s a not-fish.
Addie was his mother, and then she was not his mother, the same as for the fish; she is a not-mother, so she must be a fish.
*Vardaman Quote
“It was not here. I was there, looking. I saw. I thought it was her, but it was not. It was not my mother….It was not here because it was laying right yonder in the dirt. And now it’s all chopped up. I chopped it up. It’s laying in the kitchen in the bleeding pan, waiting to be cooked etc.”