International Journal of Aquaculture 2015, Vol.5, No. 35, 1-6
3
was used as a binder at 2% inclusion rate to improve
stability in water, increase pellet firmness, and reduce
the amount of fines produced during processing and
handling as recommended by NRC.
Pellet making and storage
The process was done by adding 450ml water per kg
of diet and stirring the mixture to form dough that had
a stiff, plastic consistency when compressed,
appropriate for pelleting. The dough was passed
through a 3mm mincer and pellets were air dried
indoors away from direct sunlight until firm to the
touch. Dry pellets were broken into suitable size and
stored in a well-ventilated room.
Meanwhile, Diets 1 and 2 sold in 50Kg bags were
bought from the stockiest called Border farmers’
cooperative in Kitwe.
Feeding the fish
Experimental diets of 30% crude protein were
presented to fish in form of pellets. Each calculated
ration was divided into two equal portions which were
fed at 9:00 and 15:00 hours. Daily feeding rate was at
5% of fish mean body weight per hapa. However,
Stickney and Kohler (Stickney and Kohler, 1990)
observed that healthy, rapidly growing fingerlings
usually eat 3-4% of their body weight daily in dry
feed.
Sampling and Data Collection
Fish measurements
The growth of fish was monitored through fortnight
sampling. Body weights and lengths for all fish from
each hapa were recorded. Precautions were taken to
minimize stress during the weighing process by
anaesthetizing the fish with clove. Standard length,
total lengths (TL) as well as wet weight (Wt) of each
fish was recorded. A graduated measuring board was
used for length (cm) measurement of fish (Goddard,
1996), and digital scale was used. At the termination
of the study, fish were harvested, weighed and
measured individually to obtain a final mean body
weight and length. Precautions were taken to
minimize stress during the weighing process by
anaesthetizing the fish with Clove, a food spice.
Various procedures were used to assess survival,
growth, feed utilization, feed intake, and condition
factor (K) and weight gains of
Oreochromis niloticus
.
Survival rate of fish
Survival was also determined. Every dead fish was
recorded to determine survival rate.
Data collection
Data was collected on a number of parameters. Some
of the formulae used to determine the various data
parameters are outlined as follows:
a) Specific Growth rate (SGR); this was calculated
from the formula adopted from Begum (Begum et al.,
2005);
SGR=
b) Percentage Increase in Weight: as proposed by De
Silva and Anderson (De Silva and Anderson, 1995),
this was calculated as follows;
%IWG=
(Wf-Wt)/Wt*100.
c) Percentage Survival Rate (%SR) = (Total number of
Fish – Total number of Dead fish/Total number of Fish)
× 100.
d) Feed conversion ratio (FCR) was calculated by
dividing the dry weight of feed offered in a given
period of time by the wet weight gained (g). FCR =
Total dry feed offered (g)/Total live weight gained by
fish (g) (Wee and Shu, 1989; Stickney, 1994).
e) Condition factor (K), an expression of the
relationship between fish length and weight was
calculated from: K = [100 x W/L (cm)
3
], where: W is
weight in grams and L is length in centimetres
(Barnabe, 1994).
In order to keep up to date with the world of
information, secondary data from published literature,
which included: journals, research papers from
libraries, the internet and government reports were
used to compare collected data with documented
information.
Data analysis
Data on growth performance, feed intake, feed
utilization, survival, condition factor and whole body
composition were recorded for subsequent analyses.
The data were entered into Microsoft Excel
spreadsheet before exporting it to SPSS 12.0 for
analysis,
specifically comparing the means,
considering that all P-values less than 0.05 indicated
significant differences (De Silva et al., 1995). All the
data was checked for assumptions of analysis of
variance. Data that did not meet normality distribution
were transformed as described by Pallant (Pallant,
