Abstract:
There are two economically important ornamental freshwater fish species found in
Sri Lanka; Dawkinsia filamentosa and Dawkinsia srilankensis. Combination of several
factors directly caused those freshwater fish species to threatened levels. Due to that,
their export was currently regulated, highlighting immediate need of conservation. The
objective of this study was to develop a new fancy hybrid variety for ornamental fish
industry. Wild caught brooders of those species were separated into male and female
and reared in cement tanks until they attained sexual maturity. Afterwards 2:1 ratio male
and female brooders were introduced into the breeding tank, provided with submerged
aquatic plants. The water quality parameters were recorded every week during the
culture period. During this culture period offspring exhibited average length, average
weight and average width of 17.29 mm, 0.047 mg and 2.55 mm, respectively. During
this period, the water temperature, water pH, dissolved oxygen, alkalinity, hardness,
nitrate, nitrite, ammonia, phosphate, turbidity and total suspended solids (TSS) in
experiment tank was 27-29 oC, 7-9, 5-7 mg/L, 110-142 mg/L, 100-123 mg/L, 0.0099-
0.0016 mg/L, 0.0015-0.0094 mg/L, 0.022-0.076 mg/L, 0.0123-0.0854 mg/L, 0.45-1.72
NTU, and 4-9 mg/L, respectively. Fulton condition factor (K) values ranged from 0.85 to
1.43, indicating varied fish health and body condition. Length frequency distribution
displayed a right skew of 1.77, suggesting growth pattern variations. Therefore, we
can conclude that, cross-breeding these D. filamentosa and D.srilankensis can create
a successful hybrid variety. Often, produced new hybrids variety, showed the color
preference of the D.filamentosa cultivar. Therefore, the newly found hybrid variety can
be exported instead of pure D. filamentosa and this will also prevent the bio-piracy of
D. filamentosa and conserve their stocks.
