This room is terrible. I look to my left and then to my right but no fish!

 Note that the subject defines the initial room in terms of what is absent. This suggests a childhood filled with unsatisfied wants.

Well, the forest seems a very good place to gather food but I doubt if there's any fish. As I look up I see a couple of tree hippos swinging from the branches, I should be cautious.

 The subject’s delusions become more intense as his piscine obsession intensifies.

The path is generally level and not very muddy which is good because I had just got my feet waxed. But then fear showed his ugly head as I saw some fottprints. Judging by the shape and size I was able to tell that they were massive cat tracks.

 The subject was incredibly vain as represented by the waxing of the feet. Note that the piscine obsession was subsumed by acute ailurophobia.

The river now in front of me is a releif; I havn't had any fish for at least two minutes now and I am starving. I splash around in the water clawing at the river bed, trying to grab the fish but there weren't any. Where were they? Something fishy was going on.

 Stagnant or still water suggests a sex drive that is absent or pathologically inactive, not by choice of the subject. Note that the subject had to force the water to move by splashing it.

I pick up the flask and examine it. It is made of the antler of a moose so it seemed pretty valuable I opened it and looked inside. A strange red liquid sploshed around in it. I tasted it and spat it back out, it wasn't fish.

 Considering that bears do not form long-term partnerships, this is highly unusual.

The key is quite shiny but not edible as i pick it out of my teeth. I closely looked at it and I saw I weird fish engraving on it. I couldn't beleive my eyes; could this be the key to the legendary fish vault? I better keep this for later.

 As most bears would be hard-pressed to figure out how to use a key, this is not an unreasonable interpretation.