Houston, Texas's Downtown Aquarium is home to four white tigers that allegedly haven't been outside for the 12 years they've lived there.

The fight over the four white tigers living at Houston, Texas’s Downtown Aquarium hinges on a particularly devastating claim: That the animals, bred in captivity and purchased by the Aquarium in 2004, have never been outside.

Actually, it’s more devastating than that: Opponents claim the animals have lived their entire lives without seeing the sun.

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But regardless of the truth of that statement — and more on that later — to see the tigers in the environment the zoo has provided for them is to be depressed at the state of modern zoos. The tigers — Nero, Marina, Coral and Reef, who are all around 12 years old — are part of the Aquarium’s “Maharaja’s Temple” attraction, which is a vaguely Eastern/Indian-themed indoor enclosure with several pools and crucially, nothing but concrete floors. While not on display, the animals’ holding areas resemble nothing so much as prison cells, with wooden-slat cots and wire cages.

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“The dungeon-like conditions that the tigers are forced to endure at Houston’s Downtown Aquarium harm their physical health and psychological well being, and deny them much that is natural and important to a tiger,” Dr. Jennifer Conrad, a veterinarian with the Animal Legal Defense Fund (ALDF), said in a statement.

The ALDF has served the Aquarium and Landry’s Inc. (the Aquarium’s owner) with a notice of intent to sue over the tigers’ living conditions. They’re offering to relocate and rehome the tigers at no cost, or failing that, sue over violations of the Endangered Species Act.

“It is cruel to confine complex, roaming carnivores such as tigers to a tiny, dark, artificial, unenriched enclosure where they never see any daylight, much less bask in sunshine,” Conrad’s statement continues. “[They] are at risk for serious long-term, debilitating injuries from being forced to live on slippery, unyielding concrete their entire lives.”

The Aquarium has defended itself to The Dodo, claiming that the animals’ exhibit has skylights that allow in some natural light and is equipped with an air system that meets the Association of Zoos & Aquarium’s standards. James Prappas, the facility’s director of animal husbandry, said that the tiger’s receive “enrichment opportunities” throughout the day.

Carney Anne Nasser, an ALDF attorney, said that changes in the Endangered Species Act since the Aquarium purchased the tigers and pending changes to the AZA’s guidelines have strengthened the case for the tigers. The AZA’s tiger care manual states that enclosures for the species should have outdoor space, vegetation and hiding space. The ALDF’s suit states that the Aquarium’s tigers have displayed signs of psychological damage because of their conditions — notably pacing and lunging at the glass wall that separates them from the public.

Landry’s says that the ALDF’s allegations constitute slander and libel. “We are aware of the proposed changes to the AZA accreditation standards and once enacted, we will make every effort to comply to the new standards. If we are unable to make such changes, we will move our tigers to a new home,” Steven Scheinthal, general counsel for Landry’s, said in a statement to the Houston Chronicle. (Nasser has said that the Aquarium would be the ones choosing where their tigers would go in the event of a rehoming, not the ALDF.)

The controversy over the tigers has stretched back to their acquisition by the Aquarium and Landry’s owner, Houston billionaire Tilman Fertitta. Initially, some city officials were concerned about the Aquarium’s suitability to house tigers, though Fertitta did bring the facility up to AZA standards and donated to global tiger conservation groups. A similar war is being fought in Denver, Colorado, where another Aquarium owned by Landry’s houses three Sumatran tigers.

Downtown Aquarium has provided PEOPLE with a statement regarding the current case, and has asked that it be run in its entirety:

“The Downtown Aquarium has been an Association of Zoos and Aquariums (AZA) accredited institution since it opened its doors in 2003 and has served as an educational experience for thousands of school children.”

“According to AZA, the care and welfare of the tigers is clearly a priority at Downtown Aquarium in Houston. From the obvious attention to detail paid during the planning and development of the facility, to resources and support provided to every required daily nuance, the animals are thriving. The Zoological Association of America (ZAA) states, Downtown Aquarium Houston has met and exceeded the USDA standards, Texas requirements for the tigers and is accredited by the two major zoological trade associations in the United States, ZAA and AZA. The Downtown Aquarium Houston is committed to providing the best care for all of the animals within their habitats and ZAA fully supports their commitment to excellence in animal care and welfare.”

“Public information available from the USDA can be found here: https://acis.aphis.edc.usda.gov/ords/f?p=116:203:0::NO“

“Public information available from the AZA can be found here: Accreditation for Houston and Denver aquariums are valid through 2020: https://www.aza.org/current-accreditation-list#H and accreditation standards: https://www.aza.org/assets/2332/aza-accreditation-standards.pdf“

“Any claim that the tigers have been deprived access to sunlight, fresh air, natural surfaces, and species appropriate environmental enrichment is false,” said James Prappas, Director of Animal Operations. “The tigers receive 24-hour cycles of sunlight and darkness as well as 10-15 air changes per hour that is appropriate for this species. The exhibit space is comprised of many natural surfaces which include: variations in floor slopes, steps, ledges, vertical space for jumping/climbing, and elevated surfaces. There is an extensive enrichment program in place that allows for species appropriate substrates to be offered such as a swimming area, grass sod, wood shavings and natural trees/logs, as well as seasonal pumpkins and Christmas trees that are all veterinarian approved.”

“The Presence of an outdoor habitat at other facilities does not indicate any better quality of life for the tigers,” added veterinarian J. Gentry, DVM. “I have cared for these tigers for the past couple of years and find them to be in both exceptional mental and physical health. The Downtown Aquarium’s tigers are truly amazing creatures and the care they receive is exceptional.”

“Both Prappas and Gentry agree that comparing wild tigers with captive tigers is equivalent to comparing feral cats to domesticated cats. Wild tigers are exposed to elements, diseases, injuries, habitat fragmentation, poaching, etc.; whereas the tigers at the Downtown Aquarium thrive in their specially designed environment that features safety, sanitation, protection from the elements, disease prevention, veterinary care, nutrition, and mental stimulation.”