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vol-13,
TIlE E1,EI\1ENTAL COMPOSITION OF OREOClIROMIS NILOTICUS TISSUES.
MOUSTAFA M. FOUDA.
Al-Azhar Unfversfty, Faculty of Scfence, Zoology Department. Nasr-Cfty, Cafro, Egypt.
AlJSTRACT
A number of fnvestfgatlons have been made on
the metal requirements for ffsh diets, but more
Infromation Is needed. Few studies of the tissue
metal contents of farmed fish have been made, and
fn order to extend our knowledge of fish metal
utilization the metal contents of some tissues
of Oreoohrmis ntlotlcus of different ages and sex
have been determined. Ffshes of circa 4.0. 8.0
and 17.0 em in standared length were used for the
estfmation of Ca, P, Mg, K, Na, Zn, Cu, and Fe
in skfn, muscle and bone. Tissues were dried.
digested and all elements excludfng’ P were measyr’ed
by atomic absorption. Singificant differences were
observed between small and large fish. Some of
these differences were as expected, e. g. increase
inCa. P. Mg, in bone with age. However, other
significant changes were found. For example, a
considerable decrease in zn content of the skin
from circa 19.0 mg % dry wefght in small ffsh to
11.6 mg% dry weight in large fish, and of the
muscle from 0.7 mg % dry weight to 0.18 mg % dry
weight. Other elements such as Fe showed lfttle
variation wfth age. No sex dffferences were observed.
