The Rawa Danau Panggang (Panggang Lake Swamp) in Hulu Sungai Utara Regency stretches as far as 5,390.7 Ha. This swamp has a large ecological, economic and fisheries resource potential. One of its potentials is lais fish (Cryptopter spp) and plankton which are food sources for these fish biota. The purpose of this study was to determine the food composition of fish lais (Cryptopter spp) and the characteristics of Rawa Danau Panggang waters. The research method used analysis of gastric contents with the largest section index based on Natarjan and Jingran in Effendi (2002) and storet methods for supporting water quality data. The research results exhibited that the food composition found in the lais fish stomach (Cryptopter spp) was diverse. Lais fish were classified as omnivores. Phytoplankton groups have 27 genera from 3 phyla, Zooplankton 6 genera from 2 divisions, and Nekton 1 genera from 1 division. The contents of the gastric stomach (Cryptopter spp) are mostly from the phytoplankton group. The highest genus is 5, namely Navicula with IP = 26.71%, Diatoma with IP = 20.33%, Tabellaria with IP = 12.43%), and Nitzschia with IP = 8.54%, which are genera of Phylum Chrysophyta, and Gonatozygon with IP = 5.35 % which is the genera of Phylum Chlorophyta. The zooplankton group consumed by this fish has far less diversity and abundance compared to phytoplankton group. Plankton consumed by lais fish is determined by the characteristics of Rawa Danau Panggang waters. DO, pH and BOD dominate the characteristics of Rawa Danau Panggang waters.