Goniobranchus tinctorius is a species of colorful sea slug, a dorid nudibranch, a marine gastropod mollusk in the family Chromodorididae.

[4] It has been reported widely in the tropical Indo-West Pacific but many of the records refer to Goniobranchus reticulatus, Goniobranchus alderi and similarly coloured, undescribed, species.

[5] Several of these have been shown to be distinct species by a DNA study.

[6] Goniobranchus tinctorius has a white mantle with an open reticulation of fine red lines.

The gills are white with two red lines on the outer surface which converge at the tip.