At the age of fourteen, Fischer was placed as a pupil with Johann Heinrich Ramberg, the fashionable court painter, by whom he was employed in painting portraits, theatrical scenery, and generally assisting his master.
In 1810 he betook himself to England, and his Hanoverian connection rendered it easy for him to obtain the patronage of royalty.
He painted miniature portraits of Queen Charlotte and the junior members of the royal family, and was employed by the Prince Regent to paint a series of military costumes.
His works were chiefly portraits in miniature, but he occasionally exhibited landscapes in watercolours.
Some sketches by him in the print room at the British Museum show spirit and intelligence, especially two pencil portraits of William Hunt and his wife.