Fischer was married to Agnes Gerlach in Feb. 1888, but she died seven years after their marriage. They had three sons, named Hermann Otto Laurenz Fischer (16. Dec. 1888 - 09. Mar. 1960) Walter (05. Jul. 1891 – 04. Nov. 1916) and Alfred (3. Oct. 1894 – 29. Mar. 1917). Alfred was killed in World War I, Walter committed suicide at the age of 25 as a result of compulsory military training. 