Samiaji, JokoEfriyeldiChristina, Reny2016-03-312016-03-312016-03-31978-979-792-437-9wahyu sari yenihttp://repository.unri.ac.id/xmlui/handle/123456789/8135The study to observe the species composition and its abundance on mudskipper fish was conducted in June-September 2013 in Dumai coastal waters of Riau Province, Indonesia. The study was carried out in providing the lack information on the biological aspects of the mudskipper from Indonesian seas in general, and of Riau's coasts in particular. The study used a survey method by selecting 3 different stations as the sampling sites. Fish samples were collected during the low tide. The quadrants were used in the field in facilitating the survey in fish abundance, whilst the identification was commenced in the Laboratory of Marine Biology of University of Riau. The results showed that a number of three species of mudskipper were successfully recorded, i.e. Baleophthalmus boddarti (Pall), Periopthalmodon schlosseri dan Periopthalmus variabilis (Eggert). In terms of abundance, the highest, 16 individuals /m2 was recorded in station I and the lowest, 9 individuals/m2, was found in station III. Based on the diversity index (H'), it was reported that the the Dumai coast had moderate diversity of the mudskipper. None of the fish was dominating the population since the dominance index (C) was very close to null from each station. It can be concluded that the habitats of mudskipper in Dumai coasts were in the state of unstable due to its E value in which also close to null.enmudskipperspecies compositionabundanceRiauUR-Proceedings