He is known by the name he went by in life. But this is a genealogy site where we seek to accurately document the genealogy of a person. If we changed his last name at birth to Fiske, that would be inaccurate.
His current last name should be Fiske and the bio should explain the name change.
You'll often see bios on Wikipedia that say, for example:
Tony Curtis (born Bernard Schwartz; June 3, 1925 – September 29, 2010) was an American film actor...
Your bio of your father could be similarly worded.