I love the depiction of gender dysphoria in this chapter. The way she has this little internal concept of herself (the guppy) floating around inside himself, completely hidden a lot of the time, and the way the rest of her body is just a shell/casing/"tank" that she lives in, and the way her fish self "aligns" with her exterior when her exterior changes to match what feels natural to her.
Also I love the line "Even if someone suspects you're a guy, there's no doubt that you're being 'who you are.'", with regards to "passing".