Diversity of fish species in several sites along the Brantas river East Java Indonesia

The purpose of this study is to describe the presence of species diversity and composition in Bratas River. Fish sampling was conducted in dry and rainy seasons in five locations, namely Batu City, Blitar City, Tulungagung regency, Jombang Regency, and Mojokerto Regency, East Java. This study collected 295 individual fishes belonging to 12 species. The 162 individuals were obtained in the dry season, while 133 individuals were captured in rainy season. The most dominant species was mujahir (Oreochromis mosambica) followed by keting (Mystus paniceps) and kutuk (Channa striata). The fish abundance significantly varied among study sites, while that of species richness and diversity did not differ significantly. Fish diversity in high elevation was the lowest, while that in relatively middle elevation was the highest. Compared to the previous report, fish species diversity in Brantas was decreasing, some species were not found. Three species were considered as exotic include Oreochromis mosambica, Clarias batracus, Oreochromis niloticus.