Twycross zoo, in Leicestershire, has warned there could be a 'mass cull' of animals after it didn't meet the requirements to get an emergency government loan.
The government has put together an £100m fund to be shared among England's zoos, but Twycross has found itself ineligible.
The criteria to get approved for funds means that a zoo needs to be 'dangerously close' to breaking point.
At the moment, a zoo would need to be within six weeks of closing down in order to be eligible.
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There is also an €800,000 (£730,000) cap on grants, which has proven difficult for larger zoos such as Twycross.
Sharon Redrobe, CEO of the zoo said: "As a group of large charity zoos we were extremely disappointed to learn that this fund effectively excludes us and is capped at too low a level.
"Whilst £100 million is indeed a large total fund, we were extremely frustrated to discover that we would be legally constrained from meeting the eligibility criteria as it requires us to have too few months of running costs left.
"Moreover, the €800,000 cap is less than one month's running costs and so is woefully inadequate for our needs and places thousands of animals at risk.
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"We urgently call on the Government to work with us on revisiting the criteria for this fund to truly help save our nation's zoos."
As a panel speaker at the recent Zoos and Aquariums All-Party Parliamentary Group (APPG) last week, she explained that the loss of the endangered species the zoo holds would be 'devastating'.
She said: "Failing animal welfare and the rundown of facilities, we all know is another road to closure.
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"The loss of a large collection of endangered species unique in the UK such as at Twycross Zoos would be devastating and when I say loss, dare I say it, potentially a mass cull as we are all in the same boat.
"No other zoo worldwide has the funds to create new enclosures immediately as they cost millions. We are all facing the same ending."
The zoo has urged the government to reassess what the rules are for funding. It usually has half a million visitors a year. Its 80-acre site has around 500 animals from 125 species.
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Twycross also has one of the largest primate collections in Europe and is one of only four places in the whole world that has all four types of great ape - gorillas, orangutans, chimpanzees and bonobos.
It's also the only zoo in Britain to have all four.
Featured Image Credit: PA