Fluminense appoint fifth coach of season
Cuca, who quit Fluminense's local rivals Flamengo in July after six months, also replaced Renato last year and will be hoping to do better than his previous effort when he lasted only nine games.
Renato, who was in his third stint at the club and had been in charge for only 12 games, became the 29th coach to lose his job among Brazil's 20 first division teams since the season started in January.
"I want to thank Renato, who has always been a correct and victorious professional whenever he has been at Fluminense," football vice-president Tote Menezes told the club's website.
Fluminense are bottom of the Brazilian championship.
Former Jamaica coach Rene Simoes was the first casualty at the club this year and he was followed by Carlos Alberto Parreira, Brazil coach at the 1994 and 2006 World Cups, who survived for four months.
Next came inexperienced Vinicius Eutropia, who lasted four games, and then Renato.
Renato last year led Fluminense to the Libertadores Cup final, the region's equivalent of the Champions League, where they lost on penalties to LDU in the final. He was fired shortly afterwards due to poor domestic form.