All but one of those in custody are supporters of the neo-Nazi group the Nordic Resistance Movement which had been given a permit to march through the city.
Several hundred people had gathered to take part in the march, many of them armed with shields and helmets. In the end, the march never actually reached the designated starting point, due to clashes with the police beforehand.
Those in custody are aged 20-50 years old and mainly from different parts of Sweden. Two of them are members of other Nordic countries and only one of them is a woman.
During the day, 35 people had been arrested, of which 12 were later released. But police told the daily Dagens Nyheter on Sunday that they are still under suspicion, and over the next few days an extensive investigation will take place, when police are going through footage and questioning witnesses.
On Tuesday and Wednesday, there will be hearings in court to decide whether the 23 will be remanded in custody.
At least two people were injured during the day, including one police officer who broke his arm.
"Given the intent that many had here today, the scenario could have been much worse," commanding officer Emilie Kullmyr told daily Dagens Nyheter.
Several people have also reported the placards that were carried by some of those marching with the NRM to the police. The placards showed big pictures of politicians and journalists with the words "criminal" next to them.
One of them is the media-expert and former journalist Willy Silberstein, who used to be the chairman of the Swedish committee against anti-semitistm.
"This is part of their attempt to scare me and others who are working against the hatred against Jews in Sweden, so that we are scared and silenced," he told Swedish Radio.