Sonneratia caseolaris commonly known as mangrove apple or Berembang in the Malay language, is a species of plant in the family Lythraceae. Area of S. caseolaris along Selangor River in Kampung Kuantan has become a natural habitat for a variety of arthropods. This study aimed to identify the species variations in arthropod communities at different selected stations along Selangor River at two different sampling times. Present study was conducted for six consecutive months (August 2010 until January 2011) at 19 selected stations along the Selangor River. Sampling was conducted once per day and night. Sweeping method by using sweep nets were used as the arthropod sampling method. Data analysis was done quantitatively to determine the composition of arthropod community. A total of 7,707 individual arthropods collected belonging to 10 different orders consisting of Coleoptera, Hymenoptera, Diptera, Neuroptera, Orthoptera, Odonata, Lepidoptera, Blattodea, Mantodea and Araneae. A total of 4,563 arthropod individuals were sampled at night, which was more than the daytime (3,144 individuals), with Station 17 recorded the highest arthropod individual out of the 19 sampling sites. During the night, the firefly, that belongs to the Lampyridae family showed the highest arthropod composition. The presence of arthropod biodiversity along the Selangor River reveals that the S. caseolaris area is important in maintaining a diverse community of fireflies and other arthropods for conservation purposes.