Sponges has been understood to host a diverse and abundant microbial community. Nevertheless, understanding on diversity and abundance of microbial community on freshwater sponges is underestimated, in comparison to investigation and research that published from marine sponges. To broaden our understanding on microbial community on freshwater sponges, we reported for the first time in Indonesia, diversity of symbiotic two freshwater sponges Eunapius carteri (Bowerbank, 1863) and Oncosclera asiatica (Manconi & Ruengsawang, 2012) from Kaliporong river in near Surabaya, East Java province Indonesia. Both freshwater sponges harbor a high microbial community that valued 1942 Operational Taxonomical Unit (OTU) that consisted of more than 1400 on E. carteri and 400 on Oncosclera asiatica OTU's. Both sponges were dominated by Proteobacteria that even reach to more than 90 percent in O. asiatica whereas, on E. carteri, besides more than 50 percent of Proteobacteria, Cyanobacteria and unknown symbiotic bacteria were also detected.
