HISTOPATHOLOGICAL STUDY OF BLACK BODY DISEASE ON GROUPER REARED IN HATCHERIES
Abstract: Mass mortality of
hatchery-reared juvenile cantang-hybrid grouper have occurred in North Bali.
The juveniles exhibited mainly black body color with abnormal swimming and
slept on the bottom of the tank. Light microscope observation revealed that
vacuolation was found in the brain tissue of the fish which showed erratic
swimming and rested on the bottom. Moreover, the results of singe step RT-PCR
diagnosis using primers specific to the T4 target segments of striped jack
nervous necrosis virus (SJNNV) RNA2 genes suggest that this virus is a fish
nodavirus. On the other hand, fish with normal swimming were not contained
vacuolation in the brain and eyes, and also negative to VNN using single step
PCR, which indicated that the fish were likely to be early infected or just
recovered from infections. These results also assumed that the virulence of the
VNN virus at North Bali waters was increased with the frequent occurrences of
mass mortality due to VNN infections. The increase in the virulence was
indicated by fast clinical symptoms leads to the black coloration of the body,
and the fish were rested and slept on the bottom of the tank. Mass mortality of
juvenile cantang grouper had occurred in North Bali. The juveniles exhibited
mainly black body colour with erratic swimming (abnormal swimming) and lies on
the bottom of the tanks. Histopathology observation showed vacuolation which
was found in the brain and eye tissues of the abnormal fish. Moreover, results
of single-step RT-PCR diagnosis using primers specific to the T4 target
segments of striped jack nervous necrosis virus (SJNNV) RNA2 genes indicated
that the fish were infected with a fish nodavirus (NNV). On the other hand, the
brain and eye tissues of the normal swimming fish were not contained vacuoles,
and also negative to VNN infections.
Keywords: black body color;
hybrid-cantang grouper; VNN
Penulis: Ketut Mahardika,
Indah Mastuti, Sudewi, Gigih Setia Wibawa
Kode Jurnal: jpperikanandd150679
