An eco-friendly integrated multi-trophic aquaculture (IMTA) farming technique was developed with the goal of resolving eutrophication by excess feed and feces as fish-farming by-products. A variety of seaweed species were tried to remove inorganic nutrients produced by fish farming. However, there have been few trials to use Sargassum fulvellum in an IMTA system, a species with a relatively wide distribution across regions with various habitat conditions, great nutrient removal efficiency and importance for human food source and industrial purposes. In this regard, our study tried to examine feasibility of using S. fulvellum in an IMTA system by analyzing growth characteristics of the species in an IMTA system comprising of rockfish (Sebastes shlegeli), sea cucumber (Stichopus japonocus) and the tried S. fulvellum (October 2011 - November 2012). We also monitored environment conditions around the system including current speed, water temperature and inorganic nutrient level as they may affect growth of S. fulvellum. S. fulvellum in the IMTA system, which were $15.72{pm}5.67mm$ long at the start of the experiment in October 2011, grew to a maximum of $1093{pm}271.13mm$ by May 2012. In September, seaweed growth was reduced to a minimum of $280{pm}70.43mm$ in length. Then, S. fulvellum began to grow again reaching $325{pm}196.19mm$ by November 2012. Wet weight of the seaweed was $4.01{pm}1.89g$ at the start of the experiment and reached a maximum of $109.26{pm}34.23g$ in May. The weight gradually declined to a low of $15.12{pm}8.40g$ in September 2012. Weight began to increase once more, rising to $39.27{pm}21.69g$ by November. During the experiment, the average velocity at the surface and the bottom was 6.5 cm/s and 3.4 cm/s, respectively. The water temperature ranged $5.0-23.5^{circ}C$, which was considered suitable for growing S. fulvellum. Results of the study indicated no significant differences in inorganic nutrients between pre- and post-IMTA installation. It was thus concluded that S. fulvellum can be a suitable seaweed species to be used in an IMTA system.