SCALE CHARACTERISTICS AND ANNULUS FORMATION OF THE CICHLID FISH TILAPIA NILOTIOA L.

SCALE CHARACTERISTICS AND ANNULUS FORMATION
OF THE CICHLID FISH TILAPIA NILOTIOA L.
By
S.EL-ZARKA, A.H. SHAHEEN
Institute of Oceanography and Fisheries, Alexandria
and
A. A. EL-ALEEM
Head of the Department of Oceanography. Faculty of Science,

University of Alexandria

INTRODUCTION

Scales of fish llsve been used extensively for the study of age and growth of
numerous marine and fresh water speciea. The Uf-le of the scale method for age
and growth studies of Tilapia species was proved to be valid: Halden, 1935; Jensen, 1958; Eler;ter and Jensen, 1960; EI-Bolock and Koura, 1960; 1961; EI-Zarka
1961.
The aim of this paper is to study scale characteristics, annulus formation,
accessory ring, time of annulus formation and relation between temperature and
time of annulus formation for Tilapia nilotica L.