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International Journal of Aquaculture, 2014, Vol.4, No.04
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25
application. Before the shrimp appear diseased or start
to die its gills turn black.
Black gill disease is reasonably easy to cure. If farmer
noticed dark-colored gills in some shrimp it is
suggested to change the water more often and also
provide more aerators. This will usually solve the
problem quickly. Addition of lime according to the pH
concentration is also recommended. Similar disease
was already reported by Lightner and Redman, (1998),
MPEDA/NACA (2003), Doughtie and Rao (1983) and
Johnson (1995) (Figure 1, 2).
Figure 1 Black gill disease
Figure 2 Black gill disease observed during sampling
2.2 IHHNV (Infectious Hypodermal and
Hematopoietic Necrosis Virus)
In the present study IHHNV (Infectious Hypodermal
and Hematopoietic Necrosis Virus) disease observed
at shrimp farms in Andrapradesh and Orissa. IHHNV
is very common in grow out ponds, especially when
the postlarvae brought from broodstock that were
raised in earthen ponds in Thailand. The white leg
shrimps with IHHNV are easy to observe because they
display a typical clinical signs of a deformed or
stunted rostrum (Figure 3). It might be bent to one
side and the body of the shrimp might be crooked.
These clinical signs will be apparent after the shrimp
have been in growing out pond for 30 days.
Figure 3 IHHNV (Infectious Hypodermal and Hematopoietic
Necrosis Virus) affected shrimps
In general the deformed shrimp will be seen in only
10-20% of the shrimp population, but if it is very
severe, 70-80% will be affected. The diseased shrimp
will grow slowly and will have a low survival rate, so
the overall yield will be lower. However, the diseased
shrimp will not usually die, they will just be weakened.
The occurrence of IHHNV is likely to rise in the
future as more farmers use post larvae produced from
brood stock from local shrimp farms than imported
ones. Outbreaks of IHHNV can occur at any time of
the year. The main risk factor is the source of the
shrimp larvae. It is very unlikely that larvae produced
from specific pathogen-free parents will get IHHNV.
The virus which causes infectious hypodermal and
haematopoietic necrosis infects many species of
shrimps including
P. monodon
,
P. japonicus
,
P.
stylirostris
,
P. vannamei
,
P. semisulcatus
,
P.
occidentalis
and
P. californiensis
. IHHN has reported
in central and South America, India, Indonesia, China,
Taiwan, Thailand, Malaysia, Philippines, Hawaii,
Gunam, French Polynesia, New Caledonia and Israel
(Bondad-Reantaso et al., 2001). The disease IHHN,