The students, who have not been named, confessed to the crime and said it was a demonstration against animals being kept in captivity.
“They are convinced what they did was in the interest of the penguin,” Dylan Bailey, manager of the Bayworld Oceanarium, told AFP. “They thought what they were doing is right. We are still discussing the matter with their legal representative. There was no malicious intention, they did not intend harm.”
However Bailey warned that three-year-old Buddy who was raised in captivity, faced certain death in the ocean.
“Although Buddy is a healthy penguin and should have enough energy to survive for up to three weeks in the wild, he is a captive raised bird that is now in an unfamiliar environment,” Bailey said. “He simply does not have the experience necessary to survive.”
Penguins normally mate for life, and Buddy has been taken away from his partner Francis.
They had two chicks, though one died previously.
Buddy, also known as penguin number 266, was discovered missing the day after the theft when he could not be found for his monthly health check.
Security camera footage showed the two students, both in their 20s, entering the penguin enclosure at night after parking their car outside. They released Buddy at nearby Pollock Beach.
Bayworld staff and volunteers have been patrolling the coast to search for Buddy, who has an identification tag on his left flipper.
He also has a microchip, but no tracker.
The Bayworld Oceanarium, which holds penguins and seals bred in captivity or injured in the wild, said it would improve security to keep out intruders.
African black-footed penguins, also known as jackass penguins due to their braying noise, have been rated as endangered since 2010 due to a rapid fall in numbers caused by commercial fishing and shortage of prey.
They are native to Angola, Mozambique, Namibia and South Africa, where they are a famous tourist attraction at Boulders Beach near Cape Town.