Aglaja tricolorata is a species of sea slug, an opisthobranch gastropod mollusc in the family Aglajidae.

It is native to the Mediterranean Sea and the tropical eastern Atlantic Ocean where it lives in shallow water on the sandy seabed.

The hind end of the mantle has two rounded lobes; the left one is extended into a long flagellum, about one fifth the length of the body; the right one conceals the bipinnate gill.

It has been observed "ploughing" through the sediment as if following a winding chemical trail left by its prey, perhaps detecting it by use of sensory hairs at the side of its mouth.

Having received sperm, the white eggs are laid in a thin string of mucus which the animal winds tightly round its body to form a tangled skein; it then emerges from the front of this cocoon, leaving the egg mass behind, possibly attaching it to the seabed.