Abstract. Santoso P, Sunadji. 2020. Use of probiotics in fish feed and clams (Pilsbryoconcha exilis) as biofilter components of aquaponic system in archipelagic dryland. Trop Drylands 3: 46-50. Aquaponic is a combination system between aquaculture and hydroponic, which is water-use efficient and is suitable to be developed in the archipelagic dryland. This study aimed to determine the effect of adding probiotics in fish feed and the use of clam (Pilsbryoconcha exilis) as additional components in the aquaponic system on feed conversion ratio, productivity of catfish (Clarias gariepinus) and aquatic spinach (Ipomoea aquatica), and removal efficiency of organic matter suspended in the aquaculture water. This study was an experimental study using a factorial treatment laid out in a completely randomized design, with three replications. The treatments applied were administration of probiotics with concentrations of 2 ml kg-1, 4 ml kg-1, and 6 ml kg-1 in feed to improve feed efficiency in catfish, thus minimizing metabolite discharges, and the use of clam in biofilter systems with a density of 50 clams m-2, 100 clams m-2, and 200 clams m-2 to improve the efficiency of absorption of cultivation effluents in the form of suspended particles. The results of ANOVA showed that the treatment of adding probiotics in the fish feed had a significant effect (P<0.05) on improving feed conversion ratio, increasing the production of catfish, and the removal efficiency, but had no significant effect (P>0.05) on aquatic spinach biomass production. Whereas the use of clams as biofilter significantly (P<0.05) improved feed conversion ratio, increased the production of catfish and aquatic spinach, also efficiently removed organic matter in the aquaponic system. The interaction of these two factors had a significant effect (P<0.05) on feed conversion ratio and aquatic spinach production, however, it had no significant effect (P>0.05) on the production of catfish and the organic matter removal efficiency. Post hoc LSD test showed that the best interaction effect was the treatment of probiotic 6 ml kg-1 and biofilter 200 clams m-2 because it generated a combination of the lowest feed conversion ratio (1.07) and the highest of aquatic spinach production (5.28 kg m-2).