Present study indicated the interactive effect between Chlorella sp. and Oscillatoria sp. to inhibited the growth of Vibrio harveyi 1526 designed using CRD involved factorial containing 4 concentrations of Chlorella sp. (0, 10x10x10x10x10, 10x10x10x10x10x10 and 10x10x10x10x10x10x10 cells/ml) and 4 concentrations of Oscillatoria sp. (0, 10x10x10, 10x10x10x10 and 10x10x10x10x10 cells/ml). After inoculated with V. harveyi 1526 for 120 hour, Oscillatoria sp. at concentrations 10x10x10, 10x10x10x10 and 10x10x10x10x10 cells/ml showed significant effect on V. harveyi 1526 reductions. Chlorella sp. at concentrations 0, 10x10x10x10x10 and 10x10x10x10x10x10 cells/ml associated with OScillatoria sp. concentrations 10x10x10, 10x10x10x10 and 10x10x10x10x10 cells/ml negatively affected survival of V. harveyi 1526 than the absence of Osccillatioria sp. in mixed culture. A similar growth inhibition of V. harveyi 1526 was observed for Chlorella sp. 10x10x10x10x10x10x10 cells/ml without Oscillatoria sp. associations. When performing for the challenge test by bathing shrimp with V. harveyi 1526 for 8 days, results showed a non-interactive effect between Chlorella and Oscillaoria inhibiting growth of V. harveyi 1526 and shrimp survival. Although the reduction of V. harveyi 1526 populations exposed to various density of Chlorella sp. and Oscillatoria sp. mixed culture, the high V. harveyi sustained in the culture also caused high shrimp mortality. The toxicity of high ammonia and nitrite nitrogen concentration from overfeeding also other caused of luminescent disease.
