He traveled to Copenhagen and attended the Royal Danish Academy of Fine Arts from 1786, winning its small silver medal in 1790.
Among his friends at the Academy were Bertel Thorvaldsen, the painter and engraver Heinrich Grosch and Carl Probsthayn.
However, he chose to specialize in flower painting, a discipline which he dedicated the rest of his career to, and was in 1804 referred to as "the best and only painter within his field".
His paintings were popular both with Frederik VI and Christian VIII and several of his works now in the Danish National Gallery must, due to their size, originally have served as room decoration.
It was supposed to serve as a residence for Princess Caroline, who was a pupil and admirer of Fritzsch, and Prince Ferdinand after their marriage.