Abstract:
The study was conducted for a period of four years four years, from July 2011 to
June 2015, with a view to producing offspring of two rapidly declining indigenous
gourami species (Trichogaster lalius and T. fasciata) of Bangladesh in captivity. Other
related issues like fecundity, larval development, breeding behavior and aquarium
market potentialities were also studied. Larvae were produced under three
treatments (T1=without hormone; T2=using hormone, PG; and T3=using hormone,
ovulin) in both experimental aquaria and earthen ponds. Young fishes were collected
from the wild sources and reared separately at the laboratory according to their sex
until breeding trial. Male and female of T. fasciata reached 7.94±2.36 cm
(10.10±1.45 g) and 8.23±2.31 cm (11.98±1.12 g) respectively, prior to breeding trial.
Whereas, male and female of T. lalius were 5.94±1.99 cm (7.14±1.33 g) and
6.02±2.13 cm (7.84±1.56 g) respectively. Mean individual fecundity was found
1273±516.81 (T. fasciata) and 160.50±26.42 (T. lalius). In aquaria, the highest
number of offspring of T. fasciata (345±49.93) was obtained in the T3 in 2014.
Whereas, maximum number of T. lalius larvae (79.67±11.85) were obtained in the T3
in 2013. In earthen ponds, the highest number of offspring of T. fasciata
(1532±249.31) was obtained in the T1 in 2014. Whereas, maximum number of T.
lalius larvae (265±39.15) were obtained in the T1 in 2014. ANOVA analyses have
revealed that all the results found in case of T1 and T3 were significantly different
from T2 in both aquaria and earthen ponds (p<0.05). Half of the total newly born T.
fasciata was observed in T3 on the 10th day after hatching followed by T1
(47%
survival). In case of T. lalius, about one-third of the total larvae survived till the 10th
day after hatching in T3 followed by T1
where about 60% larvae survived.
Relationship of the breeding performance and water quality parameters were
studied and described. Almost all the parameters were in suitable range for aquatic
organisms in all the treatments and no statistically significant differences were
recorded in maximum cases (P>0.05). Good demand of gouramies produced in
captivity was recorded and the benefit-cost ratio was found very high. The breeding
techniques in the present research could particularly be useful for both the
conservation and expansion of ornamental trade of studied species.
Description:
This thesis is Submitted to the Department of Fisheries, University of Rajshahi, Rajshahi, Bangladesh for the Degree of Master of Philosophy (MPhil)
