About four weeks ago my son, Jack, became obsessed with rainbow trout. I can’t say I was too surprised. Like my daughter, Ava, Jack has been interested in and fascinated by animals since before he could walk.

His first love is cows. Bovines of all stripes, wild and domestic, loom large in his imagination. Any given day he’ll ask what kind of animal we should pretend to be and then rattle off a list of suggestions that includes American bison, wood bison, Cape buffalo, water buffalo, musk ox, black wildebeest, blue wildebeest and so on.

He likes to spend time looking at the bison skull in our living room, an animal I shot last year, asking about what bison eat, where they live, what they like to do and other Very Important Questions. At four years old, one of his prized possessions, which he sleeps with every night, is a stuffed dairy cow he named “Cowey” that is so soft it could be made of angel kisses. Whenever I picture him in his bed it is with Cowey tucked under one arm.

He also loves to fish. When the urge strikes him, which is often, I’ll take him and his sister to a small pond in our neighborhood and they’ll hook one bluegill after another until they’ve had their fill or the panfish stop biting.

But somehow, somewhere he got trout on the brain and caught a very bad case of trout fever.

The same thing happened to me when I was a boy, though at a later age. When I was 8 or 9 years old my grandfather gave me a book on the game fish of North America and I spent hours and hours pouring over the descriptions of the various types of trout and salmon—their sleek profiles looked so exotic compared to the bass and sunfish that lived in the pond behind my house and the cool, clean water where they were found seemed to me the epitome of wilderness.

I don’t know what Jack pictured in his head when he thought of trout but I do know that the conversations he had been having at night with his grandfather, a passionate trout fisherman who lives in the Pacific Northwest, about the qualities and virtues of the rainbow—its multi-hued beauty, the disproportionate strength of its fight, its propensity to dazzle with acrobatic displays when hooked—had stoked the flames of Jack’s desire to a white-hot intensity.

“Please, please, please, please can we go fishing for a rainbow trout?” he asked. “When can we do it, Papa? Please?”

So just before Memorial Day Jack and I spent an afternoon in a rowboat on a small lake about an hour from our home. I propelled us in lazy circles hoping a trout would grab onto the shallow-diving hardbaits wobbling in the water behind us.

Then it happened. The tip of Jack’s rod started pumping up and down in a frenetic motion and I tried to keep my voice calm as I told Jack to reel, reel, reel.

I watched him move his fist in circles, bringing in line as best he could. “I think I have a bite,” he said.

He couldn’t keep up with the fish and the line went slack, his rod pointing straight up toward the sky, no longer bowed.

For an agonizing minute I watched him work the reel handle, slowly retrieving his line, which now sat in lazy coils on top of the water.

“Do I still have a fish?” he asked. I could hear desperation in his voice. My insides tightened at my inability to help my son avoid having his hopes dashed. It is a feeling of helplessness unique to parents. The fish was gone. He kept reeling.

But just as suddenly, the rod came back to life, doubled over in a deep arc. The fish was right under our boat and I could see the silver flash of the trout as its sides caught the light.

“Do you know what you have?” I said as I dipped a landing net underneath the fish.

“A bluegill?” he asked in a small voice, the idea of actually catching a trout being too much to hope for.

No, Jack, it wasn’t a bluegill. It was a trout. A rainbow trout. Your first and it was a beauty, all 14 inches of it. You caught it by yourself and after we got back to shore you couldn’t keep your hands off it.

“Papa, are you impressed of me?”

Yes my son. More than you’ll ever know.

—John Snow