The symbolism with the fish

Did anyone else notice and appreciate the symbolism there, in the underwater scenes with the schools of fish swimming about? the bigger fish eating the big fish eating the little fish was a bit heavy-handed maybe, but i liked the metaphor, nonetheless.

I think this 'underworld' is shown to be parallel to what he's dealing with: Survival against odds that one cannot possibly calculate, due to all the uncertainty in nature. Also, the school of small fish right under his raft are all unaware of what he is going through and also naturally indifferent to it. They are concerned with their own survival, which includes not being eaten by the big fish. Our man and his plight is, in reality, no more significant than the little fish, in the grand scheme of things. This also mirrors another facet of reality: Life goes on. When the small fish are first shown, the little crab, etc, under his raft they seem okay, happily swimming about (yeah, assessing the emotianal state of fish is a bit farfetched, but this just a sense I had in that scene), even though Our Man is in dire circumstances. Some time later, it is now the small fish that are under threat; yet, life still goes on, somewhere for some creature.

I'm aware that I haven't been able to explain myself as well as I could, it's a bit late where I am, but I'm certain of an existential subtext here. We take things for granted, even more so in our present age, even though we are actually powerless against the overall course of natural events. Some people, like Our Man, can be especially unlucky, but essentially all the things that happened to him could very likely happen to anyone else, in circumstance when one is struggling against the elements. There are so many things that can go wrong and so little we can do competently and efficiently, and without error.