Names were NOT changed at Ellis Island!!!! This is simply a sad old tale!
Ship manifests were prepared at the Port of Departure by steamship agents. Name changes occured after the immigrants settled in the US to adapt to a more "American sounding" name.
In fact it was ILLEGAL to tamper with names on ship manifest by immigration officials.
Here is one of numerous links about this name change mythhttp://genealogy.about.com/od/ellis_island/a/name_change.htm
Croatian Heritage Museum