It was only twenty gallons, small for an aquarium, but things got heavy quickly when you figured ten pounds for every gallon of water. He gently washed the rectangular tank out with warm water from the tap. Detergents and soaps were pollutants to such an otherwise pristine environment. He poured a blue aquarium gravel mix from the bag into a small clean bucket he had waiting on the bottom of the sink, and ran the tap over the gravel until the water ran clear. He rolled the pebbles under his fingertips. The blue was the color of the ocean from a travel postcard. It was why he had chosen such a pretty backdrop to Scotch-tape behind the glass—an image of a Greek island, white stucco houses and red roofs, alabaster cliffsides descending into that blue, blue water. He lowered the under-gravel filter plate into place at the bottom of the tank, and then carefully poured the clean gravel into the tank, making a bright azure floor three-quarters of an inch deep.

He positioned the filters and heater, and then lowered the tank into the sink under the faucet. He put a small plate on the bottom of the tank directly under the faucet stream, to keep the gravel from getting unsettled. And he turned the tap back on.

It took some time to fill the tank three-quarters full.

But he didn’t allow himself to get distracted. Instead he arranged his plants and decorations. Small plants in the front, taller in the back. He’d chosen a nice castle for this one, and a diving helmet and an arched bridge. When the water reached the three-quarters mark, he added these in, careful to press them securely into the gravel. He stepped back and admired the marine landscape.

Then he filled the tank to the top.

He unfolded the top of a small cardboard box and lifted the creature inside by the scruff of its neck.

The hamster had tiny black eyes and a quivering pink nose. Her belly was white, her head and back and ears apricot. Her little pink hands were clenched in panicked fists at her chest.

He dropped her into the tank and sealed the cover into place.

Wet, she looked like an entirely different animal. Tiny and slick, those pink feet uncurled, paws churning at the water. Her whiskers glanced against the surface, ears flat back, eyelids fluttering.

She would hold on for a while. They all did.

When she finally gave in, he’d let her rest for some time at the bottom of the tank, apricot fur feathering dreamily against the blue gravel.

And then he’d take apart the tank, wash it all, and start again.

He heard the back door open, and the rain get loud.

“There you are,” he said.

The boy streaked by behind him. His wet hospital gown clung to his scrawny knees.

The hamster swam and swam.