Various commentators suggest that the four living creatures in Revelation (ox, lion, eagle, man) represent the whole of animate creation joined to praise God.
Which raises the obvious question: Where are the fish?
You have a sky animal, a wild land animal, a domesticated land animal, and a man to lead them. But no fish. The four creatures clear do not represent the whole of animate creation (fish have souls too!), but only land and sky.
In heaven, where creation seems to already have come into its fullness, fish are absent. There’s a sea, but it’s crystal, hardly conducive to aquatic life. In the course of Revelation, everything in the sea dies (16:3). And eventually “there is no more sea” (21:1).
This makes sense if we think of sea and land, along with sea and land animals, in redemptive-historical terms. The sea is the Gentile world, land is Israel. Sea creatures are Gentiles, land creatures are Israelites.
With the coming of the new covenant, there is no longer any distinction between Jew and Gentile, sea and land. In Christ, Gentile sea creatures evolve into land creatures. As Jesus eats fish, fish are transfigured into Man.