What do we need to do when alleged father is arrested on a child support warrant and paternity was never established?

If he was arrestd on a child support warrant for your child, then there must be an existing child support order or an existing child support case pending against him.  Typically, the Florida Department of Revenue, Child Support Division, will handle these cases on your behalf.  If paternity has not yet been established and he wants a DNA test, the court will allow it at his expense.  You should contact the Florida Department of Revenue, Child Support Division.