It's not every day that you see something that utterly changes your life. Sure, there are some awesome movies that might make your summer a bit less boring, and there are amazing works of art that can capture your imagination for a while. But those grand moments that shake you to your core and make you question everything you believe are few and far between for most of us.
Luckily, we've got Antonio to turn to. And he's got life-altering moments galore, like his experience of the golden carp. When Samuel tells Antonio about the golden carp, Antonio's ideas about God, religion, and spirituality start to shift.
Samuel starts his story of the golden carp as if it is a thing of legend (and it totally is): "'A long time ago, when the earth was young and only wandering tribes touched the virgin grasslands and drank from the pure streams, a strange people came to this land'" (9.350-352).
He goes on to tell Antonio how the people angered their gods, and as punishment the gods turned the people into carp. But, Samuel explains, one god loved the people so much that he asked to be turned into a carp, too, so that he could protect them. Samuel says, "'But because he was a god they made him very big and colored him the color of gold. And they made him the lord of all the waters of the valley.'"
Samuel's description shakes old Antonio up: "'The golden carp,' I said to myself, 'a new god?'" (9.396-399). Yes, Antonio: a new god.
In Samuel's story, Antonio gains insight into the tales of the Native Americans that shaped the land long ago. This pagan god sounds as brilliant and powerful to Antonio as the Catholic God, and that's more than a little confusing for the kid. He's already seen some of Ultima's power, and the idea of the golden carp just reinforces the fact that there might be something else out there other than what he's learned from his mother and in church.
And of course, this is just the beginning. When Cico later shows Antonio the real golden carp, things will never be the same. After watching the golden carp swim by and seeing it face-to-face, Antonio comes to the realization that "the power of God failed where Ultima's worked; and then a sudden illumination of beauty and understanding flashed through my mind. This is what I expected God to do at my first Holy Communion!" (11.289-293).
Remember, Antonio is always looking for answers. His hope is that God will reveal answers when he first takes Holy Communion. But here is now, getting Big Answers to Big Questions by merely looking down at a shiny fish. What he understands from this is that Ultima's power has succeeded when God's has failed, which means he can never be perfectly satisfied with his Catholic faith. He's seen too much now.
In that sense, the golden carp serves as a symbol for an alternative to the Catholic God, and it comes to represent a type of folk wisdom and power that stems from the Native American heritage of the region—a heritage that Antonio shares. It's the heritage that Samuel alluded to in his first story about the golden carp, and it's an important piece of these characters' identities, no matter how much their Catholicism may resist it.