Ceredigion County Council is investigating how a leopard nearly escaped, when a zookeeper left its cage open during feeding time.
A group of visitors watched on at Borth Animalarium, near Aberystwyth.
Owner Alan Mumbray forgot to shut an enclosure, but noticed just as Rajah the leopard was trying to get out, and used a stepladder to stop him.
Mr Mumbray has now suspended himself from duty while inquiries are carried out.
The Animalarium website says Rajah is an African leopard, who was born at Basildon zoo. He then went to a private owner, who wanted him as a pet - but he tried to kill that owner. That meant he was no longer wanted, so came to the Animalarium.
Safety experts from Ceredigion County Council have visited the zoo, which has 150 different species. A council spokesman said: "We are investigating the incident in accordance with council policy."