THE USE OF VERTEBRAE FOR DETERMINING AGE AND GROWTH OF THE NILE CATFISH CLARIAS LAZERA (CUV. & VAL.) IN THE A.R.E.

THE USE OF VERTEBRAE FOR DETERMINING
AGE AND GROWTH OF THE NILE CATFISH
CLARIAS LAZERA (CUV. & VAL.)
IN THE A.R.E.
By
A. R. EL BOLocK
Institute of 1nland Fisheriee and Fish Cult’ure

I. INTRODUCTION
Since ancient times Clarias spp. hac;attracted the attention as an important
food fish in Egypt (Boulenger 1907). Nowadays speciesof this genus are playing
a good role as pond culture fish in many countries of the Near and Far East (El
Ila & El Bolock 1972 and Sidthmunka et al, 1966).
Rearing any fish successfully in fish ponds necessitates detailed knowledge
of its life history including age determination and rate of growth. Although
techniques of a~e and rate of growth determination have been well applied on
scaled fish (El Bolock & Koura 1960 and El Zvrka 1961). similar studies of catfish have not been widely done. El Bolock and Koura (1960) gave only some
observations on age and growth of Clarias lazera in Barrage ponds (near Cairo].
The present work is a more detailed study on the use of vertebrae in the determination of age and growth of this species. It is also a part in a series of studies
including the biology and culture of Clarias lazera in Egyptian ponds.