Abstract:
Mono sex tilapia fish (males) culture is gaining more concern over mixed
sex fish in variety of culture systems due to faster growth and larger size
than their counterpart. Mono sex culture of tilapia is not practiced in
commercial basis in Sri Lanka and the present study aimed to determine the
suitability of mono sex male tilapia to introduce into cage culture in Sri
Lanka by comparing the growth performances of mixed sex tilapia culture.
Mono sex and mixed sex fry having initial mean weights (1.23 ± 0.23g and
0.93 ± 0.25g , respectively), were stocked in 2 m-3
cages, at 25/m-3
, 50/m-3
,
75/m-3
and 100/m-3
densities, each in three replicates. Fish were hand fed
with 30% crude protein diet for 180 days. Weight of the fish in each cage
(30% from the total) and physico-chemical parameters of water were
recorded monthly. Growth parameters; mean final weight, mean weight
gain, specific growth rate and feed conversion ratio showed no significant
difference (p > 0.05) between mono sex and mixed sex GIFT in each
density class from fry to post fingerling stage (approximately 60 days).
Similar results were obtained for the growth indices for each density class
of two groups, after the whole culture period of 180 days. Stocking density
of 25 fish per m-3
in both groups indicated the highest value for all growth
parameters while increasing stocking density had significant negative effect
on all growth parameters. Present study reveals that culture of mono sex
GIFT in cages has no significant difference in growth over mixed sex
culture during fry to post advanced fingerling stages and up to sexual
maturity.
