Although, induced sex reversal and spawning in some species of grouper (giant grouper,coral trout and mouse grouper⋯.) have achieved, but survival of the larvae in thehatchery until early juvenile remains considerably low and unstable. It constrainsseriously the development of groupers aquaculture and seed export. The photosyntheticbacteria allow propagation to occur in anaerobic conditions and through respiration inaerobic condition. The photosynthetic bacteria (PSB), a single cell protein have strongability to break down ammonia and high nutrient value, contain many vital aminoacids, vitamins and carotenoids. In past, it was used in organic wastewater treatment toimproved environmental quality and clarification of sea water in fish cultivation, but lessapplication as a feed to fish larvae and zooplankton. Therefore, we will investigate thePSB to apply in grouper seed production and get some information about application ofPSB from this study. There knowledge should be helpful for improve seed productionindustry. In order to study the application of photosynthetic bacteria in groupers seedproduction, we will design a series of researches and divide to three parts. First, we useda series of methods for isolation and identification and also investigate the optimalgrowing condition of the photosynthetic bacteria, under different environmentalcondition. The second part of this study was to investigate the application ofphotosynthetic bacteria on growth of the rotifer and its dietary value for groupers.Third, was to experiment the effect of water quality on addition to groupers larvaerearing pond.