The Greater Vancouver Zoo is mourning the loss of one of its newest and most endangered residents after it died suddenly last week.

Preliminary autopsy reports show that Rakesh, one of the facility’s two newly acquired red pandas, died of a suspected fungal infection.

Rakesh and his brother Arun arrived two months ago from Winnipeg’s Assiniboine Zoo, and have been held in quarantine as required under federal zoo requirements. The brothers were transferred to B.C. under a unique Species Survival Program run by the Association of Zoos and Aquariums, which strives to breed threatened or endangered species in order to “maintain genetic diversity.”

The Greater Vancouver Zoo said its veterinarians believe Rakesh died of pulmonary blastomycosis, a disease caused by fungus living in organic matter like soil, wood and leaves.

“We had no idea that he was sick, there were no signs or symptoms,” said Menita Prasad, animal care manager for the zoo.

Because the disease isn’t common in B.C., the zoo believes Rakesh was infected before leaving Manitoba. The BC Centre for Disease Control is conducting further tests to confirm its suspicions, and the surviving brother is being treated with medication as a precaution.

“[The red pandas] have been in our quarantine facility, so they have been in sterilized containment with no access to soil at all,” Prasad said.

The head of veterinary services at the Assiniboine Zoo also told CTV News the disease was likely picked up in Winnipeg.

Originally from the Himalayas, there are less than 10,000 red pandas left on earth. The pandas, which are slightly larger than a housecat with a bear-like body, are considered endangered.

The Vancouver Humane Society says it is concerned about Rakesh’s death, considering the zoo’s history.

“We have to wait for the results of this investigation that the zoo says it’s undertaking to find out where the animal picked up this infection, but the fact is the zoo has a long and bad record for animals dying prematurely in its care,” said the society’s communications director, Peter Fricker.

The suburban zoo has come under fire in recent years for animal fatalities, including the sudden and shocking death of a two-year-old endangered tiger in 2013.

Hani, a Siberian tiger, was found dead in a cage after losing her appetite just one day before. Necropsy results showed it died of heart failure, caused by accumulation of fluid in the animal’s chest. Hani’s passing came four months after the zoo euthanized its oldest tiger, Sweetie, over health issues.

Three giraffes died at the facility between 2011 and 2012, prompting the Vancouver Humane Society to call on the zoo to remove the species altogether over concerns it couldn’t care for them properly in the cool Canadian climate.

The sudden death of four zebras following the introduction of two Cape buffalos into their enclosure in 2009 prompted an investigation by animal cruelty officials.

In 2006, the BC SPCA accused the zoo of animal cruelty for housing a hippopotamus named Hazina in an enclosure that was too small. The charge was eventually stayed when the zoo agreed to improve the animal's living space.

Critics of the zoo say it’s time to phase out exotic animals in captivity and turn the facility into a sanctuary for orphaned or injured Canadian wildlife.

"I think what people have to remember about zoos is that they are about putting animals on display for profit and these captive breeding programs are all about stocking up animals and putting them on display," said Fricker.

"This is not about conservation, they're about keeping a population of animals like this in captivity."