Abstract
ABSTRACT Fecundity studies on Clarias lazera measured both number and size distribution of ova in the ovary. Ova were separated by size with a series of 12 sieves between 1.2 and 0.1 mm and counted by gravimetric and volumetric methods. The total length-ovary weight relationship resembled that of C. gariepinus and is: Y = 7.08 × 10−8 X 3.41 (n = 11, r 2 = 0.82), where Y is the ovary weight in g and X is the total length in mm. The total length (X mm)—total ovum number (Y) relationship is: Y = 1.28 × 10−4 X 3.44 (n = 11, r 2 = 0.89). It is suggested that environmental factors probably control fecundity (number of ova) by affecting ovum size. Two peaks occur in ovum size distribution, at 0.84 and 0.10 mm, indicating that C. lazera may be capable of multiple spawning under suitable conditions. Ovum number and size distribution per unit volume were found to be relatively constant throughout the ovary with greater variation between sides than within sides. Mean number of ova per ml on each sieve is a quick met...
Published Version
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