Abstract
Sicyopus rubicundus n. sp., a sicydiine goby, is described from specimens collected in streams of Java and Bali (Indonesia). It differs from other species of this amphidromous genus by a combination of characters including a first dorsal fin with five spines in both sexes, a second dorsal fin with one spine and nine segmented rays, an anal fin with one spine and nine segmented rays, and a distinctive body colour in male.