The jail was the scene of an inmate uprising that ended with 56 dead in 2017.
At least 42 prisoners in Brazil were found strangled to death on Monday in four jails in the Amazon jungle city of Manaus, where a fight between rival prison gangs resulted in 15 dead the day before, the regional prison authority said.
A statement from the Amazonas state penitentiary department confirmed the number of deaths that took place on Monday and said authorities had regained control of the four prisons. No other details were provided.
At least 15 inmates were killed at a jail in Manaus on Sunday, with some of the inmates being stabbed with sharpened toothbrushes, while others had been strangled, Almeida said, adding that an investigation has been opened to determine the cause of the fight.
The same facility was the scene of a prison rebellion that lasted almost 20 hours and left 56 people dead in January 2017.
Brazil has the world's third largest prison population, with 726,712 inmates as of June 2016, according to official statistics.
The population is double the capacity of the nation's prisons, which in the same year was estimated to be 368,049 inmates.
In September, heavily armed men detonated explosives outside the gate of a prison in northeastern Brazil and then shot their way inside, killing a policeman and releasing 92 inmates, about half of whom were later recaptured.
The previous April, a military-style battle erupted between guards and prisoners aided by outside associates, leaving 21 people dead at a prison in Belem, near the Amazon rainforest.
The attackers in that case tried to blow up a wall to help the would-be escapees. One policeman was killed alongside 20 prisoners and their associates.
In January 2017, Brazilian police launched a massive manhunt after 184 inmates escaped from two prisons in Amazonas state following a gruesome 17-hour bloodbath between rival gangs that left 56 prisoners dead, many beheaded.
Brazil's prisons are home to the leaders of several drug trafficking organizations, and the crisis in the country's penitentiaries has had a ripple effect.
However, far-right President Jair Bolsonaro has preferred opting for a tough-hand approach, losening gun cuntrol on military rafles for instance, while granting police with more legal protection against potential accusations of human rights abuses.