Monsters of the aquatic world go on display at the River Safari today - including a fish that can knock a man unconscious with its fin.
Transporting these freshwater Leviathans to the new attraction was no mean feat.
For example, the park's six Mekong giant catfish endured an arduous three-day journey from Thailand to Singapore.
They were each kept in 2m-long heavy-duty plastic bags, packed into a container and transported more than 2,500km by truck. Two pitstops were made at Bangkok and Johor to change the water in the bags and check that the highly endangered creatures were not stressed.
"If the fish are small, we can fly them in plastic bags," said the park's assistant director of zoology Ang Cheng Chye. "But the catfish came in bags customised for them."
He added that the fish, which can grow up to 3m in length, were about 1m to 1.2m long at the time of the trip in May 2010.
The river-themed wildlife park holds its soft opening today.
Once it is fully open, it will have a boat ride and more than 5,000 animals, including the giant freshwater stingray - which can grow up to the length of a 10-seater dining table.
Dealing with the big creatures proved a challenge, said Mr Ang.
Other river monsters on display include the arapaima, a fish that can measure up to 2.75m in length, weigh as much as 200kg and knock a man unconscious with a swipe of its fin. The park also houses the world's largest amphibian, the Chinese giant salamander, which can grow up to 1.8m in length.
Transportation was not the only tricky part. Designing exhibits to house the larger creatures was no easy task either. The team had to take into account the needs of the animals, as well as those of visitors and keepers.
For example, a back room was built for a pair of giant river otters so they could be moved there while their keepers cleaned their enclosure safely.
The mammals like both land and water, so viewing platforms were built on multiple levels.
Safety was also a concern, said Mr Ang. Keepers had to be trained to gauge when the animals are stressed and may turn aggressive. "Many people think that fish are just fish, they're no big deal," he added. "But people have been killed by catfish."
The 300 species at the River Safari were selected based on how iconic they are and their status in the wild. It just so happened that the iconic and endangered ones are large as well, said Mr Ang. "I guess they are the ones we can see. Many small animals have gone extinct because we didn't notice them."
The $160 million attraction - Asia's first river-themed wildlife park - has about 42 endangered species brought in to educate the public about the need to conserve freshwater ecosystems.
It will be open from 9am to 6pm every day. Tickets during the soft opening phase cost $25 for adults, $16 for children aged between three and 12, and $12.50 for those over 60.