Volunteers have been helping rescue efforts
Many are missing and it is feared that more than 200 people in total may have drowned. Rescue efforts resumed on Friday after being halted overnight.
The MV Nyerere ferry overturned near Ukara island on its way from Bugorora.
It is thought the overloaded vessel tipped over when crowds on board moved to one side as it docked.
Rescue operations on Africa’s biggest lake have involved police and army divers, as well as small private boats and local fishermen.
The BBC’s Aboubakar Famau in Tanzania says fear has gripped residents of the Mwanza region as they wait to hear the fate of relatives who travelled on the MV Nyerere on Thursday.
“I received a call telling me that I have lost my aunt, father and my younger brother,” says Editha Josephat Magesa, a local resident.
“We are really saddened and urge the government to provide a new ferry because the old one was small and the population is big.”
Our reporter says the ferry’s engines were recently replaced after local MP Joseph Mkundi complained about the previous ones.
How did this happen?
Local media say the ferry’s official capacity was 100 people, but officials say the vessel was carrying more than 400 passengers when it capsized.
It operates on a busy route, crossing eight times a day between the islands of Ukara and Ukwerewe, which are close to Tanzania’s second-largest city of Mwanza.
The ferry was said to have been particularly busy because it was market day in Bugorora, on Ukerewe island.
The vessel was also carrying cargo, including bags of cement and maize, when it capsized around 50 metres from the shore.
It is thought that many of the passengers would not have been able to swim.