| dc.description.abstract | Two experiments were conducted to develop suitable artificial breeding tanks and breeding techniques
of a threatened catfish, Sperata aor for a period of seven (7) months from May to November, 2015.
The first experiment was conducted in cemented tanks with 3 different treatments viz. cemented
floor only, cemented floor with 6-inch muddy bottom and cemented floor with 6-inch sandy
bottom to determine their survivality in artificial condition. Each treatment was done in two
tanks with same condition. The higher survival rate was observed 93.75% in cemented tank
with sandy bottom followed by 25% in cement tank with muddy bottom and 6.25% in cemented
tank only. Then cemented tank with sandy bottom condition was selected as breeding tank. In
second experiment, two inducing agents viz. Flash hormone ((Synthetic gonadotropin releasing
hormone analog (0.002%), Domoperidin (0.998%) and Prepelin glycol (99%)) and PG (Pituitary
Gland) extracts were trialed for three different treatments with three replications for artificial
breeding. To observe the effective dose for induced breeding, the females were first injected with
Flash at the rate of 0.5 (T1), 1.0 (T2), and 1.5 (T3) ml/kg body wt. while the second doses were
performed with Flash at the rate of 1.0 (T1),1.5 (T2), and 2.0 (T3), ml/kg body wt. after 6 h from
the first dose. On the other hand, the males were administered a single dose of 1 ml Flash /kg body wt.
at the time of second dose of the female. Consequently, the females were first injected at the rate of
1.0 (T1), 1.5 (T2), and 2.0 (T3) mg PG/kg body wt. while the second doses were performed with
PG at the rate of 1.5 (T1),2.0 (T2), and 2.5 (T3), mg/kg body wt. after 6 hrs. from the first dose.
Instead, the males were administered a single dose of 2 mg PG /kg body wt. at the time of second dose
of the female. None of the trialed fishes released any eggs nor do any sperm by 72 hrs. after injection
with different doses. Then the injected brood fishes were sacrificed to know the effectiveness of two
different hormones. Histological study of gonad of S. aor indicated the presence of fully maturation
stages of both male and female treated with Flash at T2 treatment. It was full development stages in
both ovaries and testis found in Flash hormone at T2. These findings indicated that Flash hormone seems
to be highly effective in gonadal maturation. Even though treated S. aor with Flash hormone did not
response to release eggs and sperms but it is obvious that this hormone might be used in effectively to
maximize the ovulation of S. aor in hatchery. | en_US |
