I found the following Armstrongs and Fishers who belonged to the Indiana 72nd:

Company B:
William Fisher--no county listed but probably from Montgomery--trans to 44th Reg.

Company C:
James M. Armstrong from Lafayette
James Fisher-- no county listed but probably from Tippecanoe-- trans to 44th Reg.

Company G:
Samuel Armstrong from Tippecanoe County
George D. Armstrong -- no county listed but probably from Tippecanoe

Company I:
William R. Fisher from Pine Village

I hope the above info helps.

Anthony