The Utilization of

Wastewater from the smoked-fish processing industry has been known to cause water pollution in Pengadulan Estuary, Jepara. This research aimed to assess the ability of Gracilaria verrucosa as biofilter for fish processing wastewater and investigate its growth rate. This study was conducted at the Center for Brackish Water Aquaculture (BBPBAP) Jepara from January to April 2019. This study used three different G. verucosa biomass in 60 L aquarium: 150 gram (A); 200 gram (B); and 250 gram (C) and control. The parameters observed in the study were seaweed biomass, nutrient uptake by seaweed, and water quality parameters: salinity, water temperature, pH, dissolved oxygen, TSS, BOD5, ammonia (NH3), nitrate (NO3), and phosphate (PO4). The results showed that G. verrucosa decreased ammonia, phosphate, and nitrate by 67.6%, 96%, and 37.1%, respectively. The result of RGR value has increased on the 10th and 30th day whereas on the 20th day were declined. The highest RGR value obtained on the 10th day on Treatment 1, which is 2.1% per day. It can be inferred that G. verrucosa is capable of increasing the water quality and the nutrient uptake in fish processing wastewater. Therefore, G. verrucosa held potential as both ecologically and economically sustainable biofilter