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Egg Hatching, Larval Deformity and Larval Growth of Four Clariid Catfishes under Different Photoperiods

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Author(s): Borode A. O.

Journal: Journal of Animal and Veterinary Advances
ISSN 1680-5593

Volume: 4;
Issue: 1;
Start page: 156;
Date: 2005;
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ABSTRACT
Fertilized eggs of Clarias gariepinus (CG(m) X CG(f)), Heterobranchus bidorsalis (HB(m) X HB(f)), and their reciprocal hybrid crosses (CG(m) X HB(f) and CG(f) X HB(m)) were incubated. Hatched larvae were reared on a 50% protein diet for 28days under different light regimes: light(L):dark(D)24hours:0hours, LD18:6, LD12:12, LD6:18, LD0:24 and control with natural photoperiod(NP) in triplicate treatments 23 C - 24 C. Hatching time, percentage hatch, percentage deformed larvae and weight gain of larvae for the four species were recorded for the different light regimes. Results show earliest hatching time of 20hrs at LD0:24 under CG(f) X HB(m) while latest hatching time of 20.53hrs was seen at LD24:0 and LD6:18 in CG(m) X CG(f) and CG(m) X HB(f) respectively. Among crosses, it was seen that hatching time was earliest in all longer dark hours except in the CG(m) X CG(f) where longer light hours gave the highest hatching time. Significant differences (P=0.05) were found in hatching times between treatments under CG(f) X HB(m) while there were no significant differences in hatching times between treatments in the other three crosses. Hatching percentage was found to be highest in the two hybrids than their parental crosses with the overall highest occurring in the CG(f) X HB(m) cross in all the treatments. Significant differences were also found among treatments both within and among crosses. Percentage deformity ranged from 10% at the Control treatment under HB(m) X HB(f) to 35% at LD24:0 and LD6:18 of CG(m) X CG(f) and CG(m) X HB(f) respectively.. Significant differences (P = 0.05] were also found in results of treatments within individual crosses. Results of weight gain of larvae under the treatments for all four crosses were seen to be generally higher in all the longer dark hours except in CG(m) X CG(f) where longer light hours gave the highest growth performance value for this cross. Overall highest weight gain was 624mg at LD0:24 under CG(m) X HB(f) while least growth value was 80mg at the Control treatment under CG(f) X HB(m). Average daily weight gain results follow almost the same trend as in weight gain results. Among crosses highest value was recorded as 22.18mg at LD0:24 under CG(m) X HB(f) while least value was recorded as 2.79mg at the control treatment under the CG(f) X HB(m) reciprocal hybrid. Significant differences were also found in treatment results for the individual crosses and among crosses (P = 0.05]. Results here indicate that hatching and growth performance of H. bidorsalis, C. gariepinus and their reciprocal hybrids under varying photoperiods is not only determined by the light/dark period duration but also specie dependent and also due to some other inherent endogenous characteristics of the individual species which could not be determined in this experiment.
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