Abstract Photoperiod manipulation may affect the morphoanatomy of Pangasius hypopthalmus . A study aims to determine the effects of photoperiod manipulation on Pangasius hypopthalmus morphoanatomy has been conducted on July to September 2019. A one factor CRD method with 3 treatments was applied. They were control (12 hours dark), 18G (18 hours dark) and 24G (24 hours dark). …