“We started joking: What if we added fish,” recalls Hajj-Malik Lovick, 47, who has lived in the Bedford-Stuyvesant neighborhood his entire life. “Since the water is always in the puddle, why not make it something more interesting?”

After securing the edges of the tree bed with stones and bricks, they bought 100 ordinary goldfish from a pet store for $16 and put them in.

The sight of peanut-sized fish swimming around in the shallow tank quickly became a neighborhood curiosity, attracting visitors who called it “the Hancock Street Bed-Stuy Aquarium.”

But when videos and news about the fish pit circulated online, the project sparked concern among city officials and backlash from animal rights activists.

In the early hours of Wednesday morning, two local residents, Emily Campbell and Max David, carried out a rescue operation. Using nets and plastic bags, they pulled about 30 fish from the two-inch-deep water.

They say they rescued the fish from inhumane conditions. But the action sparked a heated debate about gentrification in the historically black neighborhood, which has seen an influx of young white residents in recent years.

“I’m very aware of the impact of a white yuppie coming in here and telling a guy who’s lived in the neighborhood his whole life that he doesn’t know what he’s doing,” said Campbell, a self-described fish lover who previously worked in aquaponics. “I can understand that. I just don’t want to watch 40 fish choking on their own waste in a puddle.”

Campbell, 29, said she is working to find new homes for the rescued fish and keeps many of them in aquariums in her apartment.

Several people contacted her because they were concerned about the remaining fish in the pit.

“I’m still concerned about the welfare of the fish, but I’m even more concerned about the division in the community,” she said Friday.

Those involved in the sidewalk experiment say they have enriched the neighborhood and provided a better life for goldfish, a small species typically sold as food for larger marine animals.

They feed the fish three times a day and take turns watching over them and making sure that water flows slowly from the hydrant.

“I feel like we’re helping the goldfish,” Lovick said. “These people came here and just want to make a change.”

According to Floyd Washington, one of the pond supervisors, supporters have been coming by in recent days to donate decorations such as beads and shells, as well as food.

“It brings conversations to the community,” he said. “People stop on their way to work, see something quiet and get to know their neighbors. Now we have these fish in common.”

He said the group plans to keep the fish there for about two more weeks and then donate them to children in the neighborhood.

Visitors Friday afternoon included employees of a local grocery store, an actor and a wide-eyed toddler whose nanny had heard about the fish pit on the news.

“It’s a really beautiful guerrilla intervention,” said Josh Draper, an architect who keeps his own goldfish in his Bed-Stuy apartment. “It creates a living city.”

Another passerby said the fish would soon become “rat food.”

“Nah,” Washington replied. “That’s Eric Adams,” he said, pointing to one of the few black fish that appears to be named after the city’s current mayor. “Nobody messes with him.”

Adams did not respond to a request for comment.

A spokesman for the city’s Department of Environmental Protection said there were serious safety concerns about the leaking hydrants. They sent crews out several times to repair the hydrant, but residents turned it back on.

“We love goldfish too, but we know there are better homes for them than on the sidewalk,” said agency spokeswoman Beth DeFalco.

On Friday afternoon, dozens of fish were still swimming in the pit.