Making specific reference to details or devices in the poem "A Display of Mackerel," discuss the author's view on the theme of individuality versus conformity as expressed through humans versus fish. Is "the price of gleaming" too high?

Mark Doty's poem "A Display of Mackerel" plunges the reader into the poet's stream of consciousness upon seeing the eponymous display of mackerel on ice. Doty's language is saturated with imagery relating to light, beauty, and color. Each fish is "a foot of luminosity," and the only thing breaking up their perfect radiance is the striping on their skins,

like seams of lead
in a Tiffany window.

As the poet gazes at the fish, he feels separated from their beauty the way a window-shopper is separated from the jewels in a Tiffany boutique: they flash and dazzle, but they are more than the shopper can afford. "The price of gleaming" is thus alluded to early in the poem as something essentially beyond price, desirable but unattainable.
What is the "gleaming?" It is physical beauty, yes:


Iridescent, watery
prismatics: think abalone,
the wildly rainbowed
mirror of a soapbubble sphere,
think sun on gasoline.

But the physical beauty only signifies the spiritual beauty the mackerel represent. They are "splendor, and splendor," and "all exact expressions / of the one soul." The mackerels' uniformity shows them to be a "perfect fulfilment / of heaven’s template, / mackerel essence." Each fish is an exact copy of each other fish, and every fish is the Platonic ideal of what a mackerel should be. They are perfect in themselves, so there is no need for individuality among them—individuality would mar their perfection by introducing differences. There is only one "template" for the mackerel, after all.
The price of perfection, of "gleaming," is sublimating individuality to such a "template" in order to become an "expression / of the one soul." To be beautiful in the way the mackerel are beautiful is to be "selfless," entirely lacking any sense of uniqueness:


all, all for all,
the rainbowed school
and its acres of brilliant classrooms,
in which no verb is singular,
or every one is.

To be individual is, by contrast,


to be yourself only,
unduplicatable, doomed
to be lost[.]

The poet, contemplating the mackerels' radiance, wonders what it would be like to "lose ourselves / entirely in the universe / of shimmer." Individuality is the default state of humanity, and it comes at its own price—imperfection, inconsistency, singularity instead of community. Individuals may be beautiful, but humanity as a whole will never be beautiful the way the mackerel are because it lacks the uniformity, the heavenly "template," that characterizes the mackerel. The poet struggles to imagine what it would be like to be so completely one with his fellow creatures. He longs to understand it, to partake of that beauty and that togetherness.
Is the price of gleaming too high? The poet doesn't know, and at any rate, he doesn't have the currency to pay it: humans are not schools of fish, each exact copies of one another. He can only speculate what it would be like to gleam as the mackerel do, "happy," "together," and "selfless."