Hello Wouter
According to
http://www.jagdflieger.info/ his nickname was Loisl and he was born on 1 October 1917 and served with I./LG 1, V./(Z)LG 1 and I./NJG 3. This information apparently was sourced from Jägerblatt 1974 Nr. 5 and Jägerblatt 1993 Nr. 1. Hopefully this might be of some use to you.
Horrido!
Leo