Ecsenius caeruliventris, known commonly as the bluebelly blenny in Indonesia, is a species of combtooth blenny in the genus Ecsenius. It is a tropical blenny found in the western Pacific ocean, specifically in Sulawesi, Indonesia. Male Ecsenius caeruliventris can reach a maximum length of 2.4 centimetres, while females can reach a maximum length of 2.37 centimetres; it is one of the smallest blennies in Ecsenius. The species name means "sky-blue belly" from the Latin words caeruleus and ventris, referring to the blue abdomen on the species; the common name is derived from this. The species is most similar to its sister taxon E. shirleyae and E. bandanus.[1]
Ecsenius caeruliventris are oviparous, and guard their eggs. The blennies swim at a depth range of 3–5 metres.