Danny Lyons and Cora Arcement-Buffone remember washing and installing gravel in the 400,000-gallon Gulf of Mexico tank at the Audubon Aquarium of the Americas 25 years ago.

“That was a really labor-intensive job,” said Lyons, a former dive instructor, who was called upon to create a team of 70 volunteer divers before the aquarium opened.

Twenty-five years later, the team remains about the same size, tasked with cleaning the tanks, feeding some of the fish and educating visitors.

Those volunteers and many others, along with staff and the marine-loving public, will gather this Labor Day weekend to celebrate the quarter-century mark at the city’s famed aquarium.

Mermaids, the Krewe of Zulu and Teenage Mutant Ninja Turtles will all be present for the three-day celebration.

In addition to extended hours (9 a.m. to 9 p.m.) Saturday through Monday, the celebration will include cupcakes, games and a special giveaway for the first 500 visitors each day. Tickets will be priced 25 percent off.

“The aquarium has far exceeded any expectations we had 25 years ago,” said Ron Forman, president and CEO of Audubon Nature Institute in New Orleans, which operates the facility.

“In the mid-’80s, the zoo had gone from what The New York Times had once referred to as an ‘animal ghetto’ to one of the best zoos in the country. It was that success that enabled us to move forward with the aquarium.”

Sold to the city on the promise it would boost the economy, the Aquarium has delivered from Day 1 — Sept. 1, 1990, when 13,623 people walked through the doors.

It was the largest opening day ever for an aquarium.

“There were people standing in line for three or four hours just to get in,” Forman said.

In the first year, the Aquarium welcomed over 830,000 people. By last year, that number had grown to over 23 million.

“The zoo and the aquarium now take turns in the No. 1 and No. 2 spots for top business attraction in Louisiana.

“We don’t have Disney here, or major theme parks. We have Audubon,” said Forman. “We own the daytime side of tourism.”

A small collection of animals is making the milestone alongside human caretakers.

“There aren’t a lot of animals that have been here the whole time, not just because many don’t have that long a lifespan, but because we also frequently exchange animals with other facilities to help with breeding,” said Rich Toth, managing director at the Aquarium. “That being said, we do have six penguins and three Macaws that have been with us that long.”

Toth adds that a tarpon in the Gulf of Mexico exhibit has also been there 25 years. “His name is Sinbad,” he said. “That was from back when we had few enough of the tarpons that they all had names.”

For volunteers, it’s been 25 years well spent.

While Arcement-Buffone works the Maya Reef Tank, Lyons prefers the Gulf of Mexico tank. “The hour I spend in with the sharks is the most relaxing time for me,” he said. “Once one of the sharks lost a tooth and it fell right in my hand. You can’t do that in the wild.”

With an estimated 10,400 dives over the past 25 years, Lyons is proud to say there’s never been a major injury.

“I’ve been bitten twice, he said. “A Sergeant Major fish bit the top of my ear once and the big sea turtle, Midas, bit my hair once.

“That turtle is more trouble than the sharks.”

Looking ahead to the next 25 years, Forman said the plan is to bring more festivals, and more people, to enjoy Woldenberg Park and the aquarium.

“Our dream is to make the riverfront area the city’s front porch,” he said, “and that dream is coming together piece by piece.”