REPRODUCTION IN THE NILE BOLTI

REPRODUCTION IN THE NILE BOLTI,
TILAPIA NILOTICA L.
Sexual cycle of the male
BY
A. F. A. LATIF &, B. E. S.ilDY

I.-INTRODUCTION
In the present time, a great amount of data about the seasonal changes
of the sexual gland in bony fishe has accumulated. The males of a rrurnCasterosteu aculeutu Craig-Bennett, 1931). Fundulus heteroclitus (Mat.
the rs, 19 Onchorh ynchu nerka eis L 194-3) etc. were investigated.
r -permatogenesi differs greatly.
ou d \ elopment of the sexual
zen .’ . . r inz to Kulayev (1944) the
r eoo of spermatogene i and t.he character of the
sexual products wa related to the un ynchronou entry of
1′) -permatogonia into the period of reproduction. Besides, the
an”‘Ylldilronbll1 of the process of spermatogenesis is comparatively widely
!” r d in bony fi hes (Kulayev 1944 ; Butskaya, 1955 ; Koppel, 1955). However. tlle unsynchronous ripening and discharge of sexual cells can be related
not only to unsynchronism of the process of spermatogene is but also to
unsvnchroronous progres of the wave of spermatogenesis in the different
arts of the testis fBut;;kaya. 1955 ; Partlo, 1955).
th males· independent on the character of the spawning of
– i-charge their sperms not in a short period and once but in
However, in the species whose females lay egg in a single group
in the annual sexual cycle, the males discharge their sperms in a comparatively
short period which may not be more than few days. In the fractional
pawning condition, the males can participate in spawning for weeks or even
months and in some instances during the whole year. On this account,
Dryagin (1949) has characterized two types of males, viz., 1) those with
short spawning and correspond to the females spawning a single group of
eggs, and, 2) those which have .a stretched spawning and correspond with
portional spawning females.