Journal of Stress Physiology &
Biochemistry, Vol.
8 No. 4
2012, pp. 47-54 ISSN 1997-0838
Original Text Copyright (cc) 2012 by Solomon, Okomoda
ORIGINAL
ARTICLE
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QueryDate : 2016-12-24
Cites : 1
Effect of photoperiod on some
biological parameters of Clarias gariepinus juvenile
Solomon S.G.* and V.T. Okomoda
Department
of fisheries and Aquaculture, University of Agriculture Makurdi, Nigeria
Telephone No.: +2347037275891
*E-Mail: solagabriel@yahoo.co.uk
Received July 1, 2012
Photoperiod effect on Growth
parameters and cannibalism of Clarias gariepinus have been well
documented in resent past, but little is known about the response of
other biological parameters such as, Condition factor, Shooters
composition, Body colouration and Blood glucose of this important
tropical fish species to different photoperiods, therefore the present
study was designed to evaluate these responses of the African catfish
to 24 hours of light (00D:24L), 24 hours of darkness (24D: 00L) and 12
hour light / 12 hours darkness (12D: 12L). The six weeks
experiment observed significant differences (P<0.05) in weight gain
of the fish reared at the different photoperiods with the highest value
of 92.20g+1.10 obtained in fishes reared under a photoperiod of
twenty-four hours of darkness (24D: 00L) compared to those reared under
a photoperiod of twelve hours of light and twelve hours of darkness
(12D: 12L) which had 69.80g +2.50 and the least weight gain of
59.50g+8.2 was obtained under a twenty four hours of light (00D: 24L)
photoperiod. Despite the stress induced by light which affected the
weight gain of the fish, condition factor of the fishes in the
different photoperiods did not vary significantly (P>0.05) at the
end of the experiment and were significantly lower than value obtained
at the start of the experiment. Shooters composition was highest in
00D:24L (41.5% i.e. 27 of 65) leading to high mortality (13.33%) due to
cannibalism compared to 12D: 12L (Shooters =15.27% i.e. 11 of 72,
Mortality= 4%) and 24D: 00L (Shooters=5.33% i.e. 4 of 75, Mortality=
0%) photoperiod. More so, 93.33% (70 of 75) of fish in the dark phase
(24D: 00L)exhibited Deep shiny black body colouration, while 6.67% (5
of 75) was observed of Normal fish colouration. However the fishes in
the 00D: 24L photoperiod were observed to be predominantly Lighter skin
colouration, (80% i.e. 52 of 65= lighter colouration, 18.46% i.e. 12 of
65= Normal skin coloration and 1.53 i.e. 1 of 65= Deep black body
colouration) while 12D: 12L were of Normal skin colouration (100%
Normal skin colouration), also blood glucose was observed to increase
as the light hours increased (P<0.05) with 24D: 00L photoperiod
having the highest blood glucose level of 5.7+0.5, while those in 12D:
12L had 4.4+0.3 and 24D: 00L had the least value of 3.9+0.1. This study
therefore establishes the fact that photoperiod may have no effect on
the condition factor of African catfish, while higher shooters
composition is highlighted as one of the causes of increased mortality
and could be reduced to a large extent with reduced light phase
therefore enhancing higher survival, also the use of blood glucose as
an indicator of stress in fish was justified in the present study.
Key
words: Condition factor, Shooters composition, Body coloration,
Blood glucose
