Page 190 - PARVEEN, S

ovulation, fertility and hatching rate of bata in the transparency, pH, dissolved oxygen and total
month of June. Males were administered with a alkalinity were in the range of 24.82-44.24 cm,
single dose of Ovaprim 0.15 ml/kg body weight 7.74-8.34, 3.80-5.85 mg/L and 110.10-141.23
and PG 2 mg/kg body weight showed better result mg/L, respectively. The highest weight gain
of spermiation. Growth and survival of L. bata (6.14±0.42 g) was measured in treatment T 1 and
spawn were assessed in relation to different the lowest (3.10±0.32) in treatment T 3. Final
stocking density for a rearing period of 6 weeks. length, final weight and survival of fingerlings
The experiment was designed with 3 treatments followed the same trends as weight gain.
with 3 replications each in 9 nursery ponds. The Fingerlings in treatment T 1 produced significantly
highest growth performances of the fry was higher (P < 0.05) specific growth rate (4.31±0.23)
observed in the lowest densities, i.e. in treatment than treatment T 2 and T 3. Feed conversion ratio
T 1, in terms of gain in length (L) and weight (g), at was significantly higher in treatment T 1 followed
a stocking density of 1.0 million/ha. Poor growth by treatment T 2 and T 1. Significantly higher
performance was noted in T 3, where stocking number of fingerlings was produced in treatment
density was 3.0 million/ha. The highest average T 3 than in treatment T 2 and T 1, respectively.
growth was 0.15 g/day, SGR 1 7.50±0.00%, FCR 1 Despite of this, consistently higher net benefits
.22 and survival rate of 70.97% in treatment T 1. were observed in treatment T 1 than from treatment
The physico-chemical factors were found optimum T 2 and T 3. Overall highest growth, survival, net
in all the nurseries for fish culture. So, the hatchery benefits of fingerlings were obtained at a density of
and nursery operators may use both PG and 0.5 million hatchling/ha. Therefore, of the three
Ovaprim for induction of spawning and a stocking stocking densities, 0.5 million hatchling/ha appears
density of 1 .0 million/ha for better growth to be most suitable stocking density for nursing
performance and survival rate of L. bata larvae and rearing of H. fossilis fry and fingerlings in
during nursing stage. single-stage nursery system.

529 CHAKRABORTY, B.K. & AZAD, S.A. 530 CHANDRA, K.J.; ALI, M.M. (Dept. of
(Dept. of Fisheries, Bangladesh). Rearing and Aquaculture, Bangladesh Agricultural University,
nursing of Singi, Heteropneustes fossilis (Bloch) at Mymensingh); MODAK, P.C.; IMAM, M.F.
different stocking densities in earthen nursery (Dept. of Agril. Statistics, Bangladesh Agricultural
ponds of Bangladesh. Bang. J. Life Sci., 2008, University, Mymensingh) & SULTANA, S.
20(1), 131-141. (Upazilla Fisheries Office, Raipusa Narsingdi).
Length- weight relationships and condition factor
The effects of stocking densities on growth, of Mystus vittatus (Bloch). Bang. J. Life Sci., 2006,
survival and production of Singi, Heteropneustes 18(1), 139-146.
fossilis fry and fingerlings were evaluated in a
single-stage nursery rearing system. The Length weight relationship and relative condition
experiment was conducted for six weeks in nine factor of male and female Mystus vittatus were
earthen nursery ponds of 0.026 ha each. Four-day- analyzed. A total of 111 fish were studied (86
old hatchlings were stocked at 0.5 million/ha (T 1), males and 25 females). Regression co-efficient for
0.7 million/ha (T 2) and 0.9 million/ha (T 3). At estimation of weight by total length was found to
stocking, hatchlings had a mean length and weight be 2.6386 for male and 3.3127 for female. But,
of 0.90±0.02 cm and 0.011 ±0.001 g. Water when standard length as independent variable for

183