His former wife Linda said he was admitted to hospital on Thursday with a persistent cough, The Star reported on Tuesday.
“It was found that he had fluid on his lungs.”
He stayed in hospital for observation, but collapsed on Monday morning.
“They tried to resuscitate him for 45 minutes, but he had a heart attack, most probably from the condition,” she said.
Ntoni, a self-taught bassist, joined the Dollar Brand Trio as a teenager.
The trio included world famous Cape Town pianist Abdullah Ibrahim.
In 1976, he received formal training at the Berklee School of Music in Boston.
He worked with a broad range of musicians, including Hugh Masekela and Abigail Khubeka. Recently, he collaborated with DJ Black Coffee on a revival of his hit “Usizi”.
He was long involved in music tuition, particularly of deprived black musicians during the apartheid era.
He scored and arranged the music in the book “The South African Songbook — SA Folklore Music”, which was funded by the National Heritage Council, in October.
He leaves six children and several grandchildren.
Meanwhile, Paul Mashatile, Minister of Arts and Culture also paid tribute to the fallen gallant.
Delivering his somber speech, Mashatile said:” The music industry has lost one of its own. He was a legend whom so many graduated from. May His soul rest in peace.”
Leading music industry players’ and musicians also paid their last respect to the Ntoni family.