In Thailand, the farmers always calculate the prevalence of IMN in the population and add this percentage of prevalence to the regular stocking density. They believe that IMN affected larval will die within a few days of stocking. There is no effective treatment for this disease except minimising the environmental stressors. Anderson et al. The clinical signs were similar to bacterial necrosis.
Affected larvae are often blue grey in colour and swim weakly, often in spirals.
The etiologic agent has not been identified but it is considered to be infectious in nature. Bacterial Necrosis Clinical signs of this disease are a bluish colour or discoloration, empty stomach, weak larvae falling to the bottom of the tank, and brown spots on antennae and newly formed appendages. Mixed bacterial infections were observed, with filamentous Leucothrix spp., and non filamentous bacilli and cocci present on the setae, gills and appendages. This disease is more serious in younger larvae. This disease is very common in hatcheries of both freshwater and marine shrimps.