Tilapia culture in trinidad and tobago: yet another update



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Discussion

The present study was conducted to determine the length-weight relationship and condition factor of O. niloticus from concrete ponds of Habib ADM, Hub, Balochistan.

Khallaf et al., (2003) reported differences in length –weight relationships of Oreochromis niloticus in a polluted canal compared with those of other authors in different localities and times. These differences were attributed to the effect of eutrophication and pollution on growth and other biological aspects of Oreochromis niloticus. Olurin and Aderibigbe (2006) calculated the length-weight relationship and condition factor of pond reared Juvenile Oreochromis niloticus, with a view to determining whether the fishes are in good condition. Recently Edah Bernard et al., (2010) computed the wet weight-dry weight relationship of Oreochromis niloticus (Tilapia) in significant relationship were found in all cases at (p<0.05) with correlation coefficients for males , females and pooled sexes at 0.9241, 0.9632 and 0.9586 respectively. The length-weight relationship and relative condition factor values indicated positive alometric growth (b= 4.55) of O. niloticus in the present study, which accords with the previous findings. A number of factors (e.g. sex, seasons, environmental conditions, stress, and availability of food) also affect the condition of fish. Stewart (1988) observed stress as a result of the reduction in the breeding and nursery ground of O. niloticus in Lake Turkena, Kenya, as contributing to dramatically lower condition factors. Pollution was seen to affect the condition factors of Oreochromis niloticus in Lake Mariut, Egypt (Bakhoum, 1994). The Kn values computed in the present study were ranged between 0.49- 1.84 (mean Kn 1.07 ± 0.45) confirms the findings of Hile (1936), Martin (1949) and LeCren (1951) who expressed that the exponent value usually lies between 2 and 4. In the present study the values of relative condition factor (Kn) of Oreochromis niloticus from concrete ponds of Habib ADM at Hub, Balochistan, showed ideal growth.

Table 1. Data on length and weight of a Tilapia niloticus from concrete ponds of Habib ADM, Hub, Balochistan.




No of fish groups

Length groups (cm)

Combined sexes

Mean length(cm)

Mean Weight(g)

1

15.1-20.0

16.8 ± 0.55

60.9 ± 1.55

2

20.1-25.0

23.7 ± 1.20

101.5 ± 0.99

3

25.1-30.0

29.01 ± 2.0

507.47 ± 1.25

4

30.1-35.0

31.75 ± 1.65

613.81 ± 2.30

5

35.1-40.0

37.7 ± 1.89

635.4 ± 3.35
Table 2. Relative condition factor (Kn) values for combined sexes of Tilapia niloticus from concrete ponds Habib ADM, Hub, Balochistan.

Length group

(cm)


Combine sexes

Observed weight

Calculated weight

Kn

15.1-20.0

60.9

30.19

0.49

20.1-25.0

101.50

144.54

0.73

25.1-30.0

507.47

371.53

0.91

30.1-35.0

613.81

562.34

1.42

35.1-40.0

635.4

1174.89

1.84







Mean Kn =

1. 07 ± 0.45

Fig.1. Length-weight relationship of sexes combined Oreochromis niloticus from concrete pond of Habib ADM, Hub, Balochistan (Empirical values)

Fig. 2. Log-log relationship of sexes combined Oreochromis niloticus from


concrete ponds of Habib ADM, Hub, Balochistan.



References

Bagenal, T.B. and A.T. Tesch, (1978). Conditions and growth patterns in fresh water habitats. Blackwell Scientific Publications, Oxford.

Bakhoum, S.A., (1994). Comparative study on length weight relationship and condition factors of the Oreochromis in polluted and non-polluted parts of Lake Mariut, Egypt. Bull. Natl. Inst. Oceanogr. Fish., Egypt, 20: 201-210.

Edah, B. A., A. O. Akande, C. Ayo-Olalusi, A. Olusola. (2010) Computed the wet weight-dry weight relationship of Oreochromis niloticus (Tilapia) Internet Journal of Food Safety, 12, 2010, p. 109-

Hile, R. (1936). Age and growth of Cisco, Leuhthys artedi (Le Suer) in the lake of north-eastern high lands. Bull. US. Bur. Fish., 48:211-317.

Khallaf, E. A., M. Galal and M. Authman, (2003). The Biology of Oreochromis niloticus in a polluted canal. Ecotoxicol, 12: 405-416.

LeCren, E. D. (1951). The length- weight relationship and seasonal cycle in gonad weight and condition in the perch (Perca fluviatilis). J. Anim.Ecol., 20 (4): 201 -219.

Martin, W. R. (1949). The mechanics of environmental control of body form in fishes. Univ. Toronto Stud. Biol., 56:1-91.

Olurin, K. B. and O. A. Aderibigbe. (2006) Length-weight relationship and condition factor of pond reared juvenile Oreochromis niloticus. World Journal of Zoology 1 (2): 82-85.

Pauly, T.A., (1976). General characters for the classification of the cichlid family. Ricker, W.E. (Ed.). Blackwell, Oxford.

Reynold, T.D., (1968). The biology of the clupeids in the New Volta. In: Man-made Lakes. The Accra Symposium. Ghana University Press, Accra.

Stewart, K.M., (1988). Changes in condition and maturation of the Oreochromis niloticus L. population of Ferguson’s Gulf, Lake Turkana, Kenya. J. Fish Biol., 33: 181-188.


SCALING UP OF CAGE-CUM-POND CULTURE SYSTEM OF CATFISH AND TILAPIA IN CAGES IN CARP POLYCULTURE PONDS



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