Romeo has been at the Seaquarium, where the 'loneliest whale in the world', Lolita, died earlier this year, since 1956, and he is said to have been kept alone in a small tank since at least April.
Currently, Romeo is living out his twilight days in a 30-foot-long concrete tank located in a restricted area of the aquarium.
Viewers believe that the poor manatee has health and mental problems when isolated from others and not well cared for.
Romeo, a semi-social manatee, suffers psychologically when not in pairs or groups, having been separated from his mate and the mother of his children, Juliet since his other companions were released.
The US Department of Agriculture chastised the site's operators, The Dolphin Company, earlier this month for their treatment of Romeo and general inadequate care.
A popular video of Romeo swimming in a 30ft-wide tank gained popularity after surfing legend Kelly Slater supported a petition for his release, gaining over 20,000 signatures.
A video by Urgent Seas shows Romeo, a solitary figure, spinning in circles in murky waters in a desolate park area.
Urgent Seas co-founder Phil Demers claims Romeo has been kept alone in 'Pompano pools', which have been closed to the public since April.
No one knows exactly how long he has been alone and why he has been isolated from his partner or others, but Demers said: "He was separated from Juliet a long time ago. I guess it's a breeding issue; they aren't permitted to breed manatees.
"He used to have companions when new manatees were brought in, but that was a long time ago."
Sharing the new video online, he wrote: "This video was taken on November 13, 2023, above the Miami Seaquarium.
"Romeo, a 67-year-old manatee lives in complete isolation in ever-deteriorating conditions. We must fight for Romeo!"
Kelly Slater, a former World Surf League champion, has called for public pressure on the Florida aquarium to release Romeo.
Kelly Slater told DailyMail.com: "I’m always confused and sad seeing these stories. For context, I don’t know how the manatee ended up in the aquarium or if there is a reason it can’t be returned to the wild but my thoughts on it are that manatees are very social creatures and very free, roaming large distances across the state of Florida.
"They’re the gentlest creatures in the world and such a great and recognizable mammal in our state. It seems the humane thing to do to return these animals to their rightful place in nature, along with cetaceans of all kinds which shouldn’t be in captivity at all unless terribly injured and unable to return to the wild and have quality of life.
"I grew up swimming with and admiring manatees my whole life and it would be a feel-good story to see this manatee returned safely to live out its days in the wild."
Romeo and Juliet, rescued in 1956, are local celebrities at the Miami Seaquarium. They have lived there for 66 years, with Juliet kept in a separate celebrity tank on the main site.
However, Demers asserts that Romeo has been kept in the off-limits Pompano pools, which are closed to the public.
He added: "Manatees are semi-social animals and suffer psychologically when not living in pairs or groups.
"But Romeo remains all alone. All the time."
The U.S. Department of Agriculture (USDA) has criticized the Miami Seaquarium for alleged insufficient animal care and staffing issues, citing Romeo as a senior manatee, and slammed their treatment of him.
According to the article, Romeo was housed alone in his enclosure because the three other manatees with whom he was living were released back into the wild in the spring.
Moreover, despite several tries, the Seaquarium was unable to meet the conditions for acquiring another manatee.
The USDA said: "Marine mammals, whenever known to be primarily social in the wild, must be housed in their primary enclosure with at least one compatible animal of the same or biologically related species."
The Dolphin Company's lease for a site was transferred in March 2022, leading to USDA violations and animal distress.
The aquarium was accused of inadequate veterinary care, handling, facilities, and separation. Dolphins were found eating concrete and zip ties, and one had broken ribs after an attack.
Manatees, a threatened species in the US, are facing a 'Manatee Mortality Event' in Florida due to their slow-moving nature and vulnerability to boat propellers.
The Florida Fish and Wildlife Conservation Commission declared the event after thousands of manatees died in the last three years. This year, 497 manatees have died from natural and man-made causes, with 82 killed in boat collisions and 20 killed by human contact or man-made structures like floodgates.
Patrick M. Rose, aquatic biologist and executive director at Save the Manatee Club said: "The situation as it played out was completely unacceptable. This went on much longer than it should have, but now I have confidence it will be corrected.
The Club is attempting to work with the Seaquarium to improve his conditions, he said: "Every effort is going to be made to ensure his circumstances are brought up to the appropriate levels - we aren’t going to rest until that happens."
A petition to free Romeo has over 20,000 signatures. It reads: "We demand them to do the right thing and release Romeo now!
"He should be allowed freedom, can you imagine swimming in circles in a tiny, dirty tank for decades?"
Demers plans to protest at Miami Seaquarium on Dec. 16, 2023, from 11 a.m. to 2 p.m., as mentioned in the Urgent Seas video.
He also claimed that the Seaquarium is taking legal action against him, saying: "The Miami Seaquarium's lawyers have filed a motion seeking a gag order against me.
"They're suing me for publishing drone videos of their poor treatment of animals and the atrocious conditions they live in. More to come."
Romeo is currently housed in the same Seaquarium as Lolita, the orca that died in March, a month before her scheduled retirement.
