Fins are like a bird’s wings which it uses to fly, to ascend up high into the air. In other words, by waving his wings here and there, with one wing he lifts up and with the other he pushes the air down, and with the rocking he elevates himself a bit at a time.
Similarly, the fish in the sea swim with both fins; with one fin they glide forward and with the other they push down.
And in one’s Avodah, this is expressed through ‘Love’ and ‘Fear’ of HaShem, which are the motions of ‘Rotzoi’ and ‘Shov’—in other words, ascending and expiring above to be incorporated back into the source from where he was hewn which is a ‘Rotzoi’ with ‘Love’ and great passion. And descending below which is the state of ‘Shov’ or returning due to the awe and fear of HaShem.
Accordingly, we can understand why the primary ascent of the Livyoson is through its fins, and therefore in the future which is yet to come the Livyoson will slaughter the Shor Habor specifically using its fins.
