They are gentle giants of the sea, gliding silently on wings that can span 7m, but little is known about manta rays except that they face a high risk of extinction in the wild.
To learn more about their migratory patterns and how to protect them, researchers are tagging 30 with microchips that will track their movements for up to a year.
The project by United States-based environmental group Conservation International and Resorts World Sentosa's (RWS) SEA Aquarium is the first under a five-year partnership inked in January. The tie-up will focus on conservation, public education and supporting regional projects.
The 30 mantas will be tagged in Indonesian waters, namely in Bali, Raja Ampat, Berau and Komodo, where they gather in large numbers.
These locations comprise four manta tourism sites in Indonesia, where people "pay top dollar" to swim or snorkel with them, said Conservation International's senior adviser, Dr Mark Erdmann.
The manta-ray tagging project is believed to be one of South-east Asia's largest. Each tag costs about US$6,000 (S$7,500) and can track data such as depth and temperature of the water and real-time location of the mantas using Global Positioning System technology. Manta rays are not known to be found in Singapore's waters, although they may occasionally swim past.
National University of Singapore marine biologist Chou Loke Ming said it would be useful to find out more: "In order to protect a species, we need to know more of their behaviour and movement so that we can find effective ways of conserving it."
RWS added that the data could be used by the Indonesian Ministry of Marine Affairs and Fisheries to develop conservation and tourism management policies.
Information collected from the project will also be displayed at the aquarium, one of the few in the world to keep the animals in captivity. This month, visitors can also find out more about them at a manta-ray exhibition there. Aside from viewing the three reef manta rays in the aquarium's Open Ocean Habitat section, they can take part in activities such as talks and manta feeding shows.
Although the creatures are seldom kept in aquariums due to their large size, Dr Erdmann said it "was not a welfare issue" as the rays under RWS' care are healthy. "We believe that a public aquarium plays a tremendous role in increasing awareness of ocean issues," he said.