The present study aimed to describe the length-weight(LWR), length-length(LLR) relationships, condition factors and feeding behavior for critically endangered catfish of Padma River, north-western Bangladesh, namely Rita rita (Hamilton, 1822). A total of 220 specimens, used for this study were caught by traditional fishing gear from May, 2010 to Oct, 2010. A linear relationship is shown among Total length(TL), Standard length(SL), Fork length(FL), Head length(HL), Snout length(SnL), Pre-dorsal length(PrDL), Post-dorsal length(PoDL), Anal length(AnL) and Anus length(AnsL) and Total body weight(TBW). The sample presented in thesis were large and covered reasonable size ranged from 12.9 cm to 31.9 cm. Most relationships were highly significant with ‘r’ values greater than 0.919. From the length-length relationship equations, it is observed that all length increases with increase of TL which is the expected linear relationship. The allometric co-efficient ‘b’ of the LWR was close to the negative allometric in Rita rita. Their diet consisted of a broad spectrum of food types but crustaceans were dominant, with copepodes constituting 20.7%, other non-copepode crustaceans constituted 12%.