Can Nature be one of the themes in "The Fish" by Elizabeth Bishop?

According to
critic Lloyd Schwarty Bishop is frimly in the ut pictura poesis tradition. 
That is, the use of Nature is like art, as in a painting or in a poem; nature, like art speaks
to the viewer or reader.  wants the readers of her poem "" to read the world around
them.

Thus, in Bishop's poem, the speaker, who at first is merely fishing and
catches the "battered and venerable" large fish, examines this creature of nature,
noticing the various patterns and colors he possesses, much like a work of art:

Here and there

his brown skin hung in
strips

like ancient wallpaper....He was speckled with barnacles,

fine rosettes of lime,

and infested

with tiny
white sea-lice,

and underneath two or three

rags of green
weed hung down.

And, as the speaker examines the
"tremendous fish," she is filled with sympathy and awe at the majesty and bravado of
the creature who has overcome several attempts at capturing him as she looks at the five pieces
of wire and line "Like medals with their ribbons." Furthermore, as she "stared
and stared," everything becomes "rainbow, rainbow, rainbow!" and she releases the
fish to the lake.  This rainbow represents the victory of not only the fish, but of the speaker,
as well.  For, she has read the world of nature and learned to appreciate its beauty
and sympathize with it.  Clearly, Elizabeth Bishop's poem is verse that is truly beautiful,
deeply sympathetic to nature.