Zambia's President Edgar Lungu has joined the nation in mourning the death of a fish that lived in a pond at the country's second-biggest university.

Students at Copperbelt University (CBU) lit candles and marched around campus to mourn the big bream.

The hashtag Mafishi, as the fish was affectionately known, is trending on Twitter in the southern African state.

For the last two decades CBU students have believed the fish would bring them good luck in exams.

Mafishi, meaning "Big Fish" in the local Bemba language, was thought to be at least 22 years old and had lived in the university's pond for more than 20 years, student leader Lawrence Kasonde said.

His death was still being investigated, added the president of the Copperbelt University Student's Union.

"It is yet to be buried, we are planning on embalming it," Mr Kasonde told the BBC.

Some students used to pay homage to the fish before exams, believing it brought them good luck while others saw it as a stress-reliever, says BBC Zambia reporter Kennedy Gondwe.

President Lungu quoted Indian anti-colonial campaigner Mahatma Gandhi in his message of mourning, saying on Facebook that "the greatness of a nation and its moral progress can be judged by the way its animals are treated".

"I'm glad you received a befitting send-off. We'll all miss you," he said.

Opposition leader Hakainde Hichilema said: "We stand with the CBU student community, past and present, over the death of their iconic pet Mafishi."

In other comments on Twitter, @MoffatSamora said: "May his fins rest in peace We have sent the best lawyers and accountants to come and aid the family in the preparation of his will."