A portable automatic recording system for dissolved oxygen(DO)concentrationand water temperature was designed and constructed for field studiesof fish ponds.The design constituted of:(1)DO meter with DO and temperaturesensors;(2)data logger;(3)electronic controlling unit;and(4)waterflow controlling unit.Organizing the above units enables sequential anddiscrete monitoring of pond water up to four different sources.The datacollected can be easily transfered into a microcomputer for further studies.