International Journal of Aquaculture, 2016, Vol.6, No.7, 1
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0.5 ml/Kg for the females and half dose for the males (0.25 ml/Kg). The brooders were then confined in a glass
fiber tank with synthetic substrates and an air stone aerator at a sex ratio of 2:1 (males: females) to promote
courtship and spawning overnight. Brood fish was then removed from the tank the next morning following
successful spawning. Eggs attached to the substrate were incubated at a temperature of 27.8
o
C.
Hatchlings (larvae) were reared inside the hatchery for a period of 7 days. During this period, Absorption of yolk
reserves was monitored under a microscope and found to be completely depleted after 3 days and this coincided
with anal opening. At this stage, the larvae was then said to have graduated to fry and was fed on fresh cattle
blood and planktons fed till satiation, 5 times per day for a period of 4 days to stimulate digestive activity before
being randomly allocated to fiberglass tanks outside the hatchery at a stocking density of 500 fish/tank with water
volume of 500 litres. Growth measurements and survival observations were taken for a period of 42 days.
3.2 Experimental Design and Treatments
The experiment was laid out in a Completely Randomized Design (CRD). The experiment had three treatments.
These were;
Treatment 1: control; Fry fed on boiled egg yolk + fish meal + fresh water planktons. This was
chosen as the control because it is a common diet for African catfish fry at Bunda fish farm.
Treatment 2: Fry fed on soymilk prepared from raw soybeans + fish meal + fresh water planktons
Treatment 3: Fry fed on soymilk prepared from roasted soybeans + fish meal + fresh water planktons
Each treatment was replicated three times.
3.3 Experimental feeds and feeding
Eggs, from which the yolk was extracted to feed the fry, were bought from the Bunda farm shop. The eggs were
soft boiled and the shells removed. Thereafter, the white part of the boiled eggs (albumen) was removed as well so
that only the yolks remained. The egg yolks were broken down into small crumbs and 100 ml of water was added
so that the yolk was suspended in water. Soybeans, from which Soymilk was prepared, were bought from Mitundu
market in Lilongwe district, central Malawi. One half of the purchased soybeans, equivalent to 10 kg, was roasted
till the colour turned dark brown and cracks appeared before milling for soymeal. This was done to deactivate
trypsin inhibitors. Figure 3 outlines the process of preparation of soymilk used in the experiment.
Figure 3 Steps followed during the preparation of soymilk for catfish fry feeding
