Abstract. Arfiati D, Zakiyah U, Anitasari S, Inayah ZN, Pratiwi RK. 2023. Community structure of periphyton on bamboo substrate in whiteleg shrimp (Litopenaeus vannamei Boone, 1931) pond with semi-biofloc system. Biodiversitas 24: 5080-5087. Periphyton is one aquatic organism that attaches to the substrate and can be used as a bioindicator. This study analyzes the community structure and dynamics of periphyton on bamboo substrates in whiteleg shrimp ponds with a semi-biofloc system. The study was conducted from May to July 2022. The bamboo substrate was placed in the ponds, and the samples were taken every seven days to 8 weeks. Identification and calculation of periphyton using Lackey Drop Micro transect Counting Method. The periphyton was found on a bamboo substrate in whiteleg shrimp ponds with a semi-biofloc system consisting of phyto-periphyton and zoo-periphyton. The phyto-periphyton group contains 4 phylum, 21 species, including the Bacillariophyta, Chlorophyta, Cyanophyta, and Ocrophyta. The zoo-periphyton group has 4 phylum, 10 species consisting of Arthropoda, Ciliophora, Nematoda, and Rotifera. The abundance of periphyton found changes every week. The relative abundance of phyto-periphyton includes phylum Bacillariophyta (17-69%), Chlorophyta (1-22%), Cyanophyta (30-65%), and Ocrophyta (0-25%), while zoo-periphyton includes phylum Arthropoda (0-3%), Ciliophora (69-99%), Nematodes (0-2%) and Rotifers (0-28%). The total abundance of phyto-periphyton on bamboo substrate ranged from 223,806-989,398 cells/L, while zoo-periphyton ranged from 396-1,924 individual/L. The diversity, uniformity, and dominance index of phyto-periphyton and zoo-periphyton are moderate. Water quality parameters during the study were relatively good for aquatic organism growth, except for very high total organic matter levels in several weeks.