These research findings suggest that farmers who raise fish in intensive culture ponds should adopt appropriate strategies to maintain favorable levels of dissolved oxygen (DO) in order to reduce risk of production losses, for example from periods of prolonged cloud cover which block sunlight reducing photosynthesis by phytoplankton. When light intensity was high from the afternoon to late afternoon, DO in fish ponds increased as light on ponds increased. Chlorophyll-a varied significantly by season and culture system. Intensive culture ponds contained higher concentrations of chlorophyll-a and hence higher DO levels than extensive culture ponds
