You might get a little seasick with all the up and down movement of the speaker's voice. But since it's not too long of a poem, it shouldn't be that bad. The poem's syllabic verse (check out "Form and Meter" for more on that) adds to the wavelike movement of the lines as we move predictably back and forth from one stanza to the next. And since it's called "The Fish," it makes sense that we'd have a poem that sounds like a fish moving through the water with the waves.
But beyond these wavy moves, the poem also has some alliteration in the third stanza with all those S sounds in "submerged," "shafts," "sun," "split," and "spun." The emphasis on the S helps accent the sun's role in this stanza and moves us more quickly from the cold and dark imagery of the previous stanzas. All of the enjambment we see also keeps the transitions smooth and fluid, without any interruptions from punctuation. So suddenly things are looking and sounding a whole lot brighter and energetic—kind of like life, which tends to move in waves from high points to lower ones.
These sound effects, taken with the speaker's objective, detached tone (meaning she's not getting all emotional on us), make "The Fish" sound like an aquatic ecosystem, naturally flowing from one stanza to the next without too much emotional involvement.