Abstract: The efficacy of Piper betle extract (Sireh leaves) as a functional diet in the growth performance and health status of catfish Pangasius hypophthalmus, which is also locally known as Patin, was determined via monthly sampling of catfish. The sampling was conducted to evaluate growth performance, health status and bacterial isolation from the internal organs of the fish. The feeding trials for the catfish culture were conducted at floating cage farms in Pahang River, starting from grow-out stages with an average body weight between 100 g and 200 g until harvest. During the two feeding trials, which were conducted from May to September 2017 (trial 1) and October 2017 to January 2018 (trial 2), the catfish were cultured in cages with dimensions of 10' x 12’ x 5’. The cages had a stocking density of 1500 fish per cage and were located in Kampung Bintang, Temerloh and Bera, Pahang. Two regimes of Sireh extract treatment at 1 mL kg-1 of feed (100 mg kg-1) for five times per week and three times per week were tested and compared with a control. A total of 270 catfish were sampled for body weight measurement, physical/necropsy examination of health status and bacterial isolations from the internal organs of the fish. The bacteria were cultured on tryptic soya agar and were identified using the API system (Biomérieux SA, France) after biochemical tests were conducted. In September 2017 (first trial), pathological changes such as redness on body and fins, congestion/enlargement of the spleen, kidneys and liver were observed along with the isolation of A. hydophila/caviae/sobria (2-10%). Similarly, in January 2018 (second trial), pathological changes were observed and bacterial isolation of E. tarda and E. horshinae (2.5-10%) were made. E. aerogenes and E. cloacae (2-25%) were commonly isolated from the internal organs. Overall, the treatment groups showed a statistically significant (P ≤ 0.05) increase in appetite and growth performance compared to the control group. The SirehMax™ treatment significantly improved the growth performance of catfish culture at Pahang River.