Abstract: In the present experiment the fingerlings of Puntius gonionotus (Thai Sarpunti) were stocked in the experimental rice field plot of Agronomy Field Laboratory, Bangladesh Agricultural University, to study their food and feeding habits in rice field. The fingerlings of this fish were stocked after 20 days of transplanting rice seedlings and the samplings of fishes were done once in every month from June to August. The gut contents of fishes were analysed by the numerical method and percentage of frequency of occurrence method. The water quality parameters such as temperature, Dissolved Oxygen (DO), pH, total alkalinity, chlorophyll-a, nitrate-nitrogen and phosphate-phosphorus showed monthly variations and they were within productive range. A total of 37 genera of phytoplankton belonging to Chlorophyceae, Euglenophyceae, Cyanophyceae and Bacillariophyceae were recorded in the water of the experimental plot of rice fields and in zooplankton population a total of 13 genera belonging to Rotifera, Cladocera and Copepoda were recorded. Among the 4 groups of phytoplankton Chlorophyceae was the most dominant group and Euglenophyceae was the least dominant group and in zooplankton Rotifera was recorded as the most dominant group and Cladocera as the least dominant group. However among the plankton population, phytoplankton was recorded highly dominant over zooplankton in the water of rice field. Among the genera of phytoplankton Fragilaria, Navicula, Surirella, Chlorella, Chrysococcus, Scenedesmus, Ulothrix, Euglena, Cyclotella and Oscillatoria and among the genera of zooplankton Brachionus, Cyclops, Asplanchna and Nauplius were dominant in water of the plot. The total number of genera of phytoplankton recorded in the gut contents of P. gonionotus were 36 and that of the genera of zooplankton recororded were 6. Among the 4 groups of phytoplankton Bacillariaophyceae was the most dominant and preferred group. With respect to zooplankton. P. gonionotus showed very less preferance on them. Among the genera of phytoplankton the relatively more preferred genera were Navicula, Closterium, Fragilaria, Chrysococcus, Oscillatoria, Tabellaria, Scenedesmus, Ulthrix and Aphanizomenon. P. gonionotus showed very less preference on the genera of zooplankton. P. gonionotus may be regarded as planktivores feeding mostly on phytoplankton.