Eubranchus tricolor, common name the painted balloon aeolis, is a species of sea slug, an aeolid nudibranch, a marine gastropod mollusc in the family Eubranchidae.

According to Pruvot-Fol (1954) the species Amphorina alberti Quatrefages, 1844 is a synonym of Eubranchus tricolor.

It has subsequently been reported from all around Britain and Ireland, as well as from continental coasts from Norway to Portugal and into the Mediterranean Sea.

The cerata are swollen and translucent with a narrow digestive gland which is usually dull purple in colour.

[6] Minimum recorded depth is 128 m.[6] Maximum recorded depth is 128 m.[6] Eubranchus tricolor feeds on several species of hydroids including Nemertesia antennina and Nemertesia ramosa, family Plumulariidae.