The latest victim was a 34-year-old man, Silesia regional government spokesman Krzysztof Mejer said.
Authorities gave up hope of finding any more survivors in the mangled wreckage of the hall, which collapsed during a racing pigeon event Saturday afternoon.
On Monday, officials and firefighters were deliberating whether to bring in heavy equipment to start lifting the rubble.
"They will probably also decide on whether to use dogs one more time" to check for more bodies under the wreckage, he said. Sweeps by rescue dogs from Poland and the Czech Republic found nothing Sunday.
Police experts and public prosecutors were also seeking evidence to try to determine what caused the collapse. "The site, clues, and relevant documents are being secured," Katowice police spokesman Grzegorz Wierzbiecki said.
About 500 people were in the building when its roof collapsed. The last person rescued alive was pulled out less than five hours later as temperatures plunged far below zero. About 160 people were injured.
Polish authorities said 59 of the victims had been identified by Monday afternoon. Officials have said they include at least seven foreigners: two Slovaks, two Czechs and one victim each from the Netherlands, Belgium and Germany.
Jacek Pytel, another police spokesman, said authorities had also drawn up a list of "at least 10" people reported missing, but it was unclear if they were actually at the fair. Pytel did not provide their identities.
Dirk Jespers, a 55-year-old salesman from Ghent, Belgium, was among the injured being treated in Katowice hospital.
"We were very luck to survive," Jespers, who had been selling pigeon food at the fair, Jespers told The Associated Press. "My stand was next to a pillar and a near an entrance. That's why I made it out."
Jespers, who suffered minor head and chest injuries, was waiting to hear from doctors whether he was fit enough to fly home.
Rescue crews had used hand tools to carve through the sheet metal and snarled poles of the collapsed building so as not to risk harming any survivors.
Initial reports indicated that snow caused the roof to collapse. Transport Minister Jerzy Polacek told TVN24 television that there was about more than 1 1/2 feet, of icy snow on top of it at the time.
However, the president of the Katowice company that organized the fair, Bruce Robinson, said that "the reasons are not clear" and that the firm was working with authorities to help determine them.
Grzegorz Slyszyk, a lawyer for the building's owners, said snow had been cleared regularly from the roof. He said they had heard from a Belgian witness that the floor collapsed before the roof did, raising the possibility of subsidence.
Other potential causes to be investigated include whether faulty building materials were used when the hall was constructed in 2000, and how they reacted to the contrast between bitterly cold temperatures outside and the heated interior, Slyszyk added.
One survivor, Tadeusz Dlugosz, was still at the site on Sunday, seeking information on where the body of his 26-year-old son had been taken.
"It was his idea to come to the fair ... and he found his grave there," Dlugosz said. "During the fair he was wearing only a sweater," Dlugosz said of his son. "That could be the cause of his death."
The "Pigeon 2006" exhibition at the 110,000-square-foot hall in the Bytkow district of the city opened Friday.
People who escaped have said two emergency exits were open, but other exits were locked, and that they saw people struggling to break windows to escape.
Crumpled bird cages were scattered inside the building near the entrance, and white and brown pigeons perched on the twisted rafters.
Ewa Wtorek, a veterinarian in Katowice, said she and colleagues had taken some of the animals to another building. She said many of the birds were badly injured and put to sleep.
President Lech Kaczynski declared a national period of mourning that will continue until Wednesday. Visiting the scene of the accident, Kaczynski described it as "the greatest tragedy" to hit post-communist Poland.
The leaders of France and Germany, where 15 people were killed when a skating rink collapsed in a similar accident Jan. 2, were among those who offered their condolences. Pope Benedict XVI prayed for the victims; speaking in Polish at the Vatican, he offered his "warm blessing" to the injured and the victims' families.
Thousands of people, among them Prime Minister Kazimierz Marcinkiewicz, packed Katowice's Cathedral of Christ the King for a Mass honoring the victims.