The overloaded vessel, whose passengers included scores of teachers and university students, went down early Saturday on the Chindwin River in the Sagaing region.
Some 150 people were rescued after the ferry sank on its way to Monywa, a city around 72 kilometres to the south.
But officials who believe up to 250 may have been aboard fear the death toll could top 100 as they search through the boat.
"The total death toll has now reached 53," Sa Willy Frient, the local director of social welfare and resettlement who is leading the operation, told AFP.
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"We are not sure if we can lift the whole sunken boat tonight. There could be many more dead bodies downstairs."
Local monks have held memorial services for the dead, most of whom are thought to be women.
At least four of the boat's staff have been arrested and will face legal action, according to local authorities.
Many living along the nation's flood-prone river systems rely heavily on ferries, which are often overcrowded and poorly maintained.
The European Union said it was "deeply saddened" by the disaster, and expressed "heartfelt condolences" to the families and friends of the victims.