The Dibut River in Baler, Aurora, runs along Luzon's eastern coast, located between the Pacific Ocean and the Sierra Madre Mountain range, and it serves important functions for the local ecosystem, such as agricultural irrigation, biodiversity support, and sustaining the livelihoods of nearby communities. Despite its significance, no studies have been conducted on the river's ichthyofaunal composition.  This study determined the river's ichthyofaunal composition and assessed the quantity of catch in terms of weight of fish species by lunar phases. The study collected 1,265 fish representing 22 species from 17 families using gill nets. The five major fish species comprise 85.63% of total catch biomass and are composed of the following species; Planiliza macrolepsis with 64.60%, Mesoprites cancellatus with 7.31%, Gerres erythrourus with 6.29 %, Hypoatherina temmincki with 4.03 % and Eubleekeria splendens with 3.40 %, respectively. Due to the limitations of this study, further studies related to species identification through DNA barcoding, growth by sexes, and other important growth parameters of different species are recommended for better management of the Dibut River.