Géza Vastagh descended from a dynasty of Hungarian painters in Transylvania. He began his apprenticeship in the studio of his father, György Vastagh the Elder (1834-1922).
Later he continued his education in Munich, where, in 1886, his countryman Simon Hóllosy (1857-1918) had founded a famous private art school, which attracted a large following particularly among young Hungarian and German painters. In addition, Vastagh attended courses with Gabriel von Hackl at the Munich academy.
Already as a young man, Vastagh specialised in depictions of animals, which he was soon able to sell with great success to a predominately anglophone clientele. For this reason, the bulk of his works are today in museums in Great Britain and the United States, as well as in Budapest. He found the subjects for his studies after nature not only in the great zoos of northern Europe, as for example in this drawing from Berlin, but also made multiple journeys to North Africa for this purpose.