Viral Nervous Necrosis (VNN) is considered to be a serious disease of several marine fish species. VNN causes 100% mortality in larval stages while lower losses have been reported in juveniles and adult fish. Thus, this case study was conducted to detect the presence or absence of VNN, associated factors and genotypes in Malaysian hybrid groupers. A batch of hybrid groupers were followed from larvae stages to the market size. The hybrid groupers, water samples, live feed and artificial fish pellet were collected at each time of sampling from day 0 till 180 from a West Malaysian hybrid grouper hatchery. The PCR analysis was conducted using the primers designed by Nishizawa et al. (1994) and Pena et al. (2008). A total of 113 out of 146 pooled samples including hybrid grouper, water and artificial fish pellet demonstrated positive results for the presence of VNN. The clinical signs observed in the samples include darkened skin, deformation of backbone, distended abdomen, skin lesion and fin erosion. VNN was present throughout the life stages of the hybrid grouper with the first detection at day 10. VNN associated factors identified in this study include high temperature, high DO, high salinity, ammonia, fish size (adult) and life stages (age). Detection of VNN in water samples demonstrated evidence of horizontal transmission. All the nucleotide sequences in this study revealed high nucleotide identity of 88% to 100% to each other, Striped Jack Nervous Necrosis (SJNNV) and reassortant strain RGNNV/SJNNV isolate of 430.2004 (GenBank accession number JN189932.1) (n=26). The phylogenetic analysis showed the presence of quasispecies in each positive samples based on type of samples and life stages. This is the first detection of VNN with high similarities to RGNNV/SJNNV reassortants in Malaysian hybrid groupers and South East Asia.