My goldfish died.

Such a passing does not make world news; life passes every minute of every day. But such a passing becomes news of the heart for reasons unique to that heart. This heart; my heart.

The goldfish came into my life as a prank. Some teenagers put the little thing in a zip-lock sandwich bag, placed it on our front porch, rang the doorbell then dashed back to their car. The intent was that when my wife or I stepped out the door to see who had rung the doorbell, the hapless goldfish would be crushed by an unwary foot.

It wasn’t.

Instead, the goldfish found a home in my aquarium. This is where the story of the heart begins.

Fourth grade was a wretched year of never-ending conflict with a teacher who disliked me with unusual fervor. We made each other miserable.

Fifth grade was mostly neutral, but sixth grade was wonderful. When I walked into Mr. Reese’s classroom for the first time in 1963, my eyes instantly fixed on the two 10-gallon aquariums he had bubbling away on the countertop.

Not only did Mr. Reese let me help take care of the tanks and their occupants, but when school ended that next spring, he let me take one aquarium home just for the summer. Aquariums have been a part of my life for 49 of the last 50 years.

Sometimes, I bought fishes from a store; sometimes, I caught and kept wild local fishes. Other times, I kept wildlife other than fishes.

In my tanks, I have watched fishes, crayfishes and snails lay eggs. I have watched tadpoles grow legs and turn into frogs. I have watched dragonfly nymphs molt again and again until the day arrived when they became winged adults. I have watched clams and leeches.

Of all that I have done with life in a glass box filled with water, nothing has been more important than taking what I have learned and experienced into the field that I might more clearly understand the life of pond and lake and reservoir, of spring and creek and river.

Every day that I cared for that goldfish gave me occasion to think about life aquatic. As interesting as I find crustaceans and sponges, and as interesting as hydras and spirogyra algae are beneath the lens of a microscope, the fishes are the ones that call me back.

A minnow from Asia — “minnow” is a name for a family of fishes and has nothing to do with diminutive size — the goldfish has been selectively bred in the manner of chickens and melons, dogs and beans, horses and corn.

We now have bug-eyed goldfishes, double-tailed goldfishes, black goldfishes, white goldfishes and black-and-white goldfishes. Though some individual koi appear to resemble goldfish, the resemblance is a coincidence of color. Koi are domesticated common carp, another member of the minnow family.

People often disregard common carp with some disdain, a sentiment lavished on many species. Roger Tory Peterson, father of the book concept known as the field guide, once remarked to me that birders forget that starlings are birds, too.

I could expand his remark to goldfish. One rescued goldfish that I came to know particularly well lived its life like a living scrapbook of the heart. My heart.

Kevin J. Cook is a freelance writer and naturalist based in Loveland. His Wildlife Window column appears in the Reporter-Herald every Thursday.