Isaac Vischjager was a son of Jacob Vischjager and Vrouwtje Lelie. He was born in Amsterdam on 30 October 1903. After primary school, he went to the night school and got a job at a menswear company, where he eventually became a warehouse manager and were he was able to work for 23 years.
On 11 April 1935 he married Clara Witteboon in Amsterdam, a daughter of Abraham Witteboon and Vogeltje van West…