Abstract
A total of 1521 fishes were surveyed during the studyperiod of 1984-87. The size of the fish varied from 5 to 31.0cm. The highest percentage (27.87%) was observed in 29.0 em
size group. The pooled data for three years showed that thehighest percentage (11.97%) belong to 23.0 cm. However, thehighest percentage of fishes were caught belong to size group
of 20-24 cm. Generally the males are smaller than females of
the same age group.
The length-weight relationship of the above collectedfishes were:
Log W = -1.6991 + 2.6958 Log L
The length-weight relationships in all the cases studied
were found to be linear in logarithmic form. The regressionco-efficient was nearer to 3 and the correlation co-efficientbetween length and weight were stronger.
The sex ratio of this species is 1/1. However, during
breeding season the female were caught in higher numbers but
later it was available almost equally.
The fish exhibited only one spawning season: from May to
July in Mymensingh district (Bangladesh) based on
gonadosomatic index and gonad histology. The breeding season
coincides with the highest GSI, incereasing rainfall (highest)
increasing humidity, and increasing water temperature (highest),
The monthly doses required to breed the fish have
determined both for HCG and PG. At the peak season, the
requirement was minimum. The doses of various other PG
been
dosehave
been reported. The changes occurred in the body paramentershave been presented. The size of the female did not affect the
spawning of fish. The single and double dose of injectionsdid not make significant difference except in the ovulation time.The spawning behaviour have been recorded in captivity
after hormone injection. Both male and female took part activelyduring spawning.
The fecundity of the fish varied from 3781 (21.0 cm and
100.0 g fish) to 14,792 (31.0 cm and 232.5 g fish). The
linear relationship exists between fecundity-total length,feundity-body weight, fecundity-gonad weight and body weightovary weight.
The testis and ovary remain viable for freedingn upto 24-
30 hours and 34 hours respectively within the body after
injection. But during post-ovulation or testis dissection the
duration came down drastically.
The eggs were brownish yellow, demersal and adhesivehaving a diameter of 1.4 + 0.004 which hatched out at 24.0
1.2 hours after fertilization. The larvae commence feeding from
4-5 days when yolk sac was almost absorbed. It breathed air
after 10 days.
Tubifex worm, zooplankton and artemia in live form proved
best food for the larvae. A feeding frequency of two times
per day with zooplankton and four initially but later three
times with tubifex was required up to 38th day of age. The
stocking density recommended was 4 fish per liter a water level
upto 16 cm a water temperature of 28-32°С.