The utilization of bagasse for additional culture medium of sludge worm (Tubifex sp.) was suppossed to examine the effect of the addition of fermented bagasse in the culture medium on the sludge worm biomass. This research used completely randomized design with 5 treatments and 3 replications. The treatments were 100% bagasse (A); 75% bagasse & 25% mud fields (B); 50% bagasse & 50% mud fields (C); 25% bagasse & 75% mud fields (D); and 100% mud fields (E). Data were analyzed using analysis of variance (ANOVA) test and then continued with Least Significant Difference (LSD) test. The result showed that the best treatment was D treatment (25% bagasse fermented and 75% field mud) with the population 167,618 ind/m2 dan biomass 380.94 gr/m2. Water quality of cultured were temperature of 27°C, pH of 6,9-7,2, dissolved oxygen of 3,6-4,7 ppm, and ammonia of 0,06-2,37 ppm.