| Naga
- The *ICLARM Quarterly
Vol.
25, No. 2 (April – June 2002)
Aquabyte
Effect
of Diazinon 60 EC on Anabas testudineus, Channa
punctatus and Barbodes gonionotus
M.Z. Rahman, Z. Hossain, M.F.A.
Mollah and G.U. Ahmed
Abstract
Anabas testudineus, Channa punctatus and Barbodes
gonionotus were exposed to 5.62, 6.25, 6.87,
7.50, 8.12 and 8.75 ppm; 1.13, 2.26, 3.39, 4.52,
5.65 and 6.78 ppm; and 2.00, 2.50, 3.00, 3.50,
4.00 and 4.50 ppm of Diazinon 60 EC, respectively.
The median lethal concentration (LC50)
values of Diazinon 60 EC on A. testudineus,
C. punctatus and B. gonionotus were 6.55,
3.09 and 2.72 ppm for 96 hrs of exposure. The
fish species showed several abnormal behaviors
which included restlessness, arena movements,
loss of equilibrium, increased opercular activities,
strong spasm, paralysis and sudden quick movements
during the exposure. For histopathological studies,
A. testudineus, C. punctatus and B. gonionotus
were exposed for 7 days to sublethal concentrations
of 1.13 and 3.75 ppm; 1.13 and 2.26 ppm; and 1.13
and 2.26 ppm of Diazinon 60 EC, respectively.
Hypertrophy, necrosis and pyknosis of hepatocytes,
pyknosis and degenerative changes such as necrosis
of tubular and haematopoietic cells of kidney
were the major histopathological effects.
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Article (PDF 142 KB)
Heterogeneous
Individual Growth of Macrobrachium rosenbergii
Male Morphotypes
K. Ranjeet and
B.M. Kurup
Abstract
In a single cohort of small freshwater prawn,
Macrobrachium rosenbergii, the size range
of females in the population is rather small.
However, among the males, three major morphotypes
are found and each has a distinct size category.
The differential growth pattern in males, termed
"heterogeneous individual growth" (HIG),
is a major bottleneck confronting the profitability
of farming this species. An attempt is made to
understand the cause and impact of HIG on the
culture system and methods by which HIG could
be minimized in growout in order to maximize the
market yield structure of the harvested population.
View
Article (PDF 209 KB)
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