Development of Biomarker in Surface Water Quality Monitoring by Using Culture Fishery (Case Study: Saguling Reservoir, West Java, Indonesia) Suphia Rahmawati 1 , Dwina Roosmini 2 and Indah Rachmatiah Siti Salami 3 1 Environmental Management Technology Research Group, Faculty of Civil and Environmental Engineering, Institut Teknologi Bandung , jl. Ganesha 10, Bandung, 40132, Indonesia email: suphia_rahmawati@yahoo.com 2 Environmental Management Technology Research Group, Faculty of Civil and Environmental Engineering, Institut Teknologi Bandung , jl. Ganesha 10, Bandung, 40132, Indonesia email: droosmini@bdg.centrin.net.id 3 Environmental Management Technology Research Group, Faculty of Civil and Environmental Engineering, Institut Teknologi Bandung , jl. Ganesha 10, Bandung, 40132, Indonesia email: indahrss@yahoo.com Abstract Saguling reservoir is one of reservoir that located in West Java Province in Indonesia. Originally this reservoir was plan for single purpose to generate the electricity and received water from Citarum River. Water quality in this reservoir is depends on the water quality of Citarum River which have face significant change because of the increased of land use along Citarum River basin and ineffective effluent and stream standard. Parameter that tends to increased is heavy metal especially mercury from industries and agriculture discharge. The studies conduct in Saguling culture fishery using two dominant species of fish Oreochromis niloticus and Cyprianus carpio as biomarker. Mercury concentration in fish was analyzing based on Standard Nasional Indonesia (SNI) 06-264-1991. High concentration of mercury found in Oreochromis niloticus (16.8470 ppb wetweight ) and 12.8943 ppb wetweight for Cyprianus carpio. These results are still below the permissible limit but still high compare to control samples. These sampling point was located in the same area and received water discharge from agriculture and domestic area which have contribution of mercury discharge. Biomarker by culture fisheries can be used as monitoring method to maintain the water quality in Saguling reservoir. Keywords: Biomarker, Mercury, Saguling, Reservoir, Oreochromis niloticus, Cyprianus carpio 1. Introduction Saguling reservoir is an artificial lake that located at 6:50 S, 107:25E, 643 m above sea level or 40 km from Bandung City . The surrounding area of Saguling reservoir was hilly, while the river that goes to reservoir has many tributaries. This condition makes the Saguling reservoir different with other reservoir in West Java such as Jatiluhur and Cirata Reservoir. Population that lived surrounding reservoir is dense and predominately by farmer population with extensive agricultural lands. The catchments area of the reservoir or the upper Citarum river faced high population pressure especially from farmer population. This reservoir also received water from Citarum river basin with 7 sub river basins which are the water quantity and quality depend on the quality of Citarum river Basin. Upper Citarum river receives discharge water from domestic and industrial activities resulting water quality degradation such as the increasing of heavy metals concentration. The rapid change of land