What is the narrator's obsession with the axolotls in "Axolotl"?

The narrator’s apparent obsession with axolotls is key to what Cortazar's story suggests about how our minds relate to the world. “Axolotl” seems to describe the narrator observing axolotls in a zoo aquarium, but by the end of the story, it seems to be narrated by an axolotl staring out at a human. The story makes this shift in an extremely subtle way, so you might characterize the story as a Mobius strip: two sides with a single, unbroken surface.

The story begins with the narrator mentioning his visits to a zoo/botanical garden in Paris (the Jardin des Plantes), and how he became obsessed with the axolotls in the aquarium:

I would lean up against the iron bar in front of the tanks and set to watching them. There's nothing strange in this, because after the first minute I knew that we were linked, that something infinitely lost and distant kept pulling us together.

The use of the first-person plural voice (“we,” “our,” etc.) links the axolotls and the narrator, making this the first step in the story’s strange twist. There’s a subtle difference between saying “I knew that we were linked” and saying “I knew that I was linked to the axolotls.” The former immediately brings the “self” (the narrator) and the “other” (the axolotls) together.

Instead of looking on the outside world in terms of what is separate from ourselves or outside of our minds, the narrator sees something ostensibly external as an intimate part of who he is. There’s a powerful philosophical idea at play here. On one hand, to imagine that our minds are fundamentally shaped by what is outside of us suggests that we are less psychologically independent than we might normally imagine. To look at things from the flipside, however (as “Axolotl” loves to do), if our minds and the external world are so linked, then our minds also have some role in shaping what we see.

And that’s exactly what we observe as the narrative of “Axolotl” unfolds – by its end, we see that the narrator’s observation of the axolotls, or what he imagines them to be like, becomes the axolotl. When the story ends with the axolotl-narrator staring out on the world, we have come full circle (or full twist): the observation of the axolotls initially shaped the narrator’s mind, but then the narrator's mind observing the axolotls changed the very notion of what the axolotls were.

The story also suggests why axolotls, of all things, were what the narrator became obsessed with in this way. He states:

It was their quietness that made me lean toward them fascinated the first time I saw the axolotls. Obscurely I seemed to understand their secret will, to abolish space and time with an indifferent immobility.

The silent, undeveloped nature of the axolotls (who live their lives as perpetual adolescents, biologically speaking) became the perfect vehicle for the narrator’s musings.