Goniobranchus epicurius is a species of colourful sea slug called a dorid nudibranch, a marine gastropod mollusc in the family Chromodorididae.

[4][5] Goniobranchus epicurius is a chromodorid nudibranch with a translucent white mantle.

There are thin opaque white longitudinal lines and small orange spots on the mantle.

The rhinophores and gills are translucent, edged with opaque white pigment.

Specimens with a heavy dusting of red pigment and no white lines on the mantle match the original description.