Well, most attacks on migrants are from migrants. As example in the first 9 month of last year, migrants killed 44 people, 6 of them were Germans and 38 of them were other migrants. I guess if we talk about violence against migrants, the stats look similar. Most will come from other migrants because that are the people who see each other every day.
Every attack is bad but most of them (on people, not those on the buildings with swastikas) are not from "Nazis"
What people always seem to forget is the situation. The numbers are high but stuff like that simply happens if you put hundred people in a hall to live there together for months or something. The situation is totally different to where everyone has his own house and doesn't clash against other people on a daily basis.
As more people have to live together on small space, as more of this you will see. It's still sad but foreseeable, it will happen with every group of people. Same like you always hear about rapes in cloisters or other accomodations where many live together.