This study investigated the occurence of Eristalis larvae and its association with water quality parameters in the mangrove ecosystem of Langensari Village, Blanakan District, Subang Regency, West Java, Indonesia. Water and macrozoobenthos samples were obtained from three locations denoting distinct environmental settings: Station 1 (St-1) near a fish auction site, Station 2 (St-2) adjacent to community ponds, and Station 3 (St-3) near the Blanakan Estuary, Subang Regency, West Java Indonesia. Water quality assessments were carried out to provide a thorough characterization of environmental conditions in Langensari and to investigate the correlation between water quality and macrozoobenthos bioindicator responses. The measures of water quality encompassed temperature, pH, salinity, total suspended solids (TSS), dissolved oxygen (DO), chemical oxygen demand (COD), and biological oxygen demand (BOD). Identification of macrozoobenthos was conducted at the BRIN Marine Research Laboratory using a Leica M205C microscope. The findings indicated spatial variability in water quality across stations. All stations showed elevated COD and BOD levels, suggesting considerable organic contamination. The prevalence of macrozoobenthos was minimal, with only one Eristalis larva documented at St-2, and no macrozoobenthos detected at St-1 or St-3. The presence of Eristalis larvae may indicate their tolerance to organically enriched environments. Alongside water quality, habitat attributes such as water flow, mangrove presence, temperature, and salinity seemed to affect macrozoobenthos distribution. The data suggest that the distribution of macrozoobenthos in Langensari is indicative of both water quality deterioration and overarching habitat constraints.
