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vol-2FOOD AND FEEDING HABITS OF SOME EGYPTIAN FISHES IN
LAKE QUARUN.
Part I. Tilapia zillii (Gerv.) B. According to different length groups
By
Dr. B.A. ABDEL-MALEK
Institute of Inland Fisheries and Fish Culture.
ABSTRACTThe material was collected over a three-months period from May to
July 1969. The results so obtained were analysed by using the occurrence &I the points methods. According to the present data, three
major groups were formed r- A·group: 30-45 mm ] Bvgroups 46-
90mm &I C·group: 91-250 mm.
In the three different length groups of Bolti, the plant material were
the chieffood items. The importance of the animal food increasesto
– a certain extent as the fish grows larger.
It is of interest to mention, that the small fi’sh (30.45 mm long)
feed on a limited number of small slow-movingorganisms &I as they
grow-larger their diet becomesmore varied The change in composit.,
ion of the diet asthe fishgrowsis an expressionof increase in the minimum size of the organism eaten. Small fish are unable to swallow
the relatively large organisms such as molluscs (gastropods &I Abra
ovata) &I polychaete.s (Nereis BFP.).
It is clearly seen, that as the fish grows larger the percentage of
empty alimentary canals increases. This presumably indioatea that
the fish eat more sporadically as they grow
