The suspects, aged between 14 and 68, have been accused of criminal damage, wounding, and criminal intimidation.
Officers believed some of them have triad links, and different gangs were behind the debt collection groups.
Inspector Chen Tsz-chuen said the suspects had allegedly attacked debtors, put up loan-collection letters, and had issued threats, including calls and texts.
In one particular case, the inspector said, multiple locations of a cryptocurrency exchange chain had been damaged and splashed with red paint.
He added that police had arrested the suspects at the scene before more damage was made.
Chen said the youngest arrestee, a 14-year-old student, was believed to have played a relatively frontline role in the debt collection process, and said police urged young people not to break the law.
“At the same time, we call on parents to pay attention to their children to see whether they might have the intention to make a quick buck, or have income from unknown sources, in order to prevent them from falling into the wrong path,” he said.
Two of the suspects have been charged with criminal damage, and officers said more arrests could be made.