In the darkness of Waikiki Aquarium, shafts of morning sun fell through large, illuminated glass tanks where unicorn fish, manini, yellow tangs, butterflyfish, Moorish idols and a tiny cleaner wrasse in fluorescent rainbow shave-ice colors darted and flitted, while in smaller tanks sea horses and weedy-looking sea dragons slowly bobbed as if dancing courtly underwater quadrilles.

They were all beautiful and fascinating to watch, but there were no spectators: The aquarium has been closed to the public due to COVID-19 since mid-March, with small shifts of staff coming in to care for the animals and keep the facilities operating, said Andrew Rossiter, aquarium director.

“I shouldn’t say this, but it’s actually been really nice with no visitors,” Rossiter said Tuesday as he contemplated a glowing, floor-to-ceiling cylinder, filled with pulsing moon jellyfish, which he likened to “a living lava lamp.”

>> PHOTOS: Reef life gets a breather from visitors at Waikiki Aquarium

Quiet and peaceful with the air-conditioning and bright signage lights switched off, “it’s very relaxing to bring a chair and sit in here,” Rossiter added, noting that the aquarium normally receives about 280,000 visitors, including 30,000 schoolchildren on field trips, over the course of a year.

Asked if the absence of humans might also be restful for the aquarium’s animals, he said, “It’s only anecdotal, but they do look a lot more relaxed (without) little kids who bang on the glass.”

“It’s possible the fish are feeling less distractions, and perhaps some are a little more curious now, but there’s been no overt aggression or mating behavior,” he added as a leopard­-spotted, zebra shark swam by in the tank behind him.

Erin Kelly, a biologist and aquarium research associate, said the lack of people was a big change and the different environment took adjusting for the intelligent octopus. “I’m sure when people start coming back, he’ll probably spend a few days hiding in his den before coming out and interacting.”

Biologist Helene Meehl, who tends to the seahorses and weedy sea dragons, said the male sea horses were also coping with a change: They had been separated from the females to prevent their reproducing.

“We’ve got the big boys in a basket within the tank because we don’t have enough staff on duty right now to produce enough feed for a growing population of sea horses, which require up to 3,000 pieces of live (algae) a day,” Meehl said, explaining that sea horses lack stomachs and so must eat constantly.

The feed, including a special variety for baby sea horses, is cultivated on site, Kelly said, and the staff rigorously tests and regulates the temperature and purity of tank water, which is drawn from the reef and the aquarium’s well, for all the exhibits, but sea horses and sea dragons are especially sensitive and susceptible to disease.

“IT WOULD be a great study to look at whether the behavior of fishes changes in our exhibits when there are no visitors here,” Rossiter said, “but research is on hold at the moment because we’re short-staffed due to COVID.”

On the other hand, he said, as he strolled outdoors into the bright sun by the sea, the reef ecosystem in this area of the Waikiki Marine Life Conservation District was benefiting without tourists walking on coral and scattering fish food despite the ”do not feed the fish ” sign on the aquarium fence.

Rossiter was glad this practice, which drew large schools of fish fighting for the “junk food” that interrupted their natural diet, had stopped, he said as he watched a few long, greenbacked bonefish swimming calmly in the clear shallows.

But just that morning, he added, for the first time in more than six weeks, he looked out his office window and saw a man dumping a bucket of fish food into the sea.

As he walked back through the aquarium yard, a series of honks and bellows came from the monk seal, who had hauled himself out onto the concrete deck of his pool.

“He knows it’s feeding time,” Rossiter said.

Indoors, the sea dragons, added to the aquarium in fall 2018, were also being fed; some of the dreamlike creatures, who resembled long-limbed Balinese dancers in branching headdresses, made a beeline for the column of food flecks, but others turned away.

“I keep track of them to see who’s feeding and who’s not — when they go off their feed, it could mean they’re producing eggs,” Meehl said, adding that each individual looks different to her and has a name based on its markings.

—

AQUARIUM SCHOOLING

Although the Waikiki Aquarium is closed, public education programs are still conducted online:

>> When: Wednesday, from 3:30 to 4:30 pm,

>> What: Webinar on king tides, sea level rise and how to volunteer as a community scientist.

>> On the net: For more information, and to make donations to the nonprofit organization, which has no revenue coming in during the coronavirus shutdown, go to waikikiaquarium.org.