"Eel Tail" is an extremely repetitive poem, as the speaker returns to specific words, phrases, and grammatical constructions again and again throughout. All this repetition makes sense: the speaker insists that it's just about impossible to ever get a good look at the eels, so all "you" can do is keep "looking and looking." The poem keeps circling back on itself, conveying the sense that the eels are continually just out of reach.

For example, the word "sometimes" (twice also followed by "you see") and the phrase "you keep" (followed by "looking" or "finding") pop up at the start of multiple lines:

• "sometimes you see mudfish,"
• "you keep looking and looking for those"
• "sometimes its just a smirk of ripples
• "you keep looking and looking for those"
• "you keep finding those sea-veins still"
• "sometimes you see that whip-thin"

There's repetition within these phrases as well, as with the diacope of the phrase "looking and looking" (a phrase that itself appears twice in the poem). Again, the repetitive phrasing relays just how extensive this "looking" is; it seems to never end, so "you keep" going and going. (The diacope of "sucking and sucking" likewise creates emphasis; the eels' are endlessly "sucking" up the water of the marsh.)

The poem also repeats an entire chunk of lines three times, creating a refrain:

and then as soon as you see them
gone
untranslatable hissed interruptions
unspeakable wide chapped lips

it's the wind again [...] and when it clears

The repetition of these lines emphasizes the slippery nature of the eels: over and over, "you" spot the eels only for them to vanish so quickly that you're not sure you ever saw them in the first place. Time and again, you think "it's the wind" causing ripples along the surface of the water, rustling the reeds, or whooshing past your ears. And "when" the wind "clears," you start the search anew.

At the very end of the poem, however, the speaker varies the refrain:

• First, "and then as soon as you see them" turns into "and then as soon as you see her." The speaker has zoomed in on one specific eel here, making the image more precise by using the pronoun "her." You're not focusing on a mass of anonymous thems, but one specific creature.
• Next, the speaker repeats the previous line almost word for word: "and then as soon as you say so." This parallelism ramps up the drama; there's now an extra beat between the "and then" part of the refrain and the "gone" that readers have come to expect. You're so close to the eel that it seems, for a moment, like you might actually get a hold of her; alas, she evades your grasp once more.