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5.4 Data collection
5.4.1 Water quality parameters
During the experiment, water quality parameters such
as temperature, dissolved oxygen (DO) concentration
and pH were measured daily using Hydrolab, Model
“Multi 340I/SET. Total dissolved solid particles (TDS),
conductivity and salinity were also measured once in
two weeks interval with the same instrument.
5.4.2 Sampling of fish and measuring of growth
parameters
50% of fish were sampled every two weeks for their
body weight and body length measurement. Length
and weight of the fish were measured using ruler and
digital weight balance (Ohaus portable balance),
respectively. Mortality of the fish was also registered
throughout the experiment. Sexual maturity and other
effects were also registered for all strains.
5.4.3 Data analysis
Based on the data collected during the experiment,
growth performance, and feed conversion ratio Futon
condition factor, gross fish yield and rate of survival
were calculated as described by Ridha (2006) as
follows:
SGR (%/day) =
〔
(lnFMBW
－
lnIMBW)/d
〕
× 100
FCR = FI (g)/ MBWG (g)
FCF = FMBW / FMBL
3
× 100
GFY = FMBW/TWv
Survival rate (%) = (NSF
－
NDF/NSF) × 100
Where: - FBW and IBW are the final and initial mean
body weight, respectively
- d is the time interval in days during the study period
- FI is amount of feed intake (g) in dry weight basis
- MBWG and FMBL are mean body weight gain in
gram (g) and final mean body length fish (cm),
respectively
- TWv is the total water volume used for culturing
fish in meter cube (m
3
)
- NSF and NDF are Number of stocked and dead
fish during, respectively
5.5 Statistical analysis
Mean growth performance parameters, survival and
feed utilization were analyzed for all strains at
different sampling periods using analysis of variance
(General Linear Model). T-test and Turkey test were
used to identify the mean value that causes a
significant difference for the analysis of variance.
Statistical significance was determined at p < 0.05. All
calculation was performed using Minitab 15 and SPSS
14 versions of statistical software.
Acknowledgement
We would like to express our appreciate to all staffs of the National Fishery
and Other Aquatic Resources Research Centre (NFARRC) and Ziway
Fisheries Resource Centre who collaborated in different ways while we
were conducting our experiment. We would also indebted to the Norwegian
Government State Educational Loan Fund.
Author’s Contribution
Professor Gjoen, H.MAB contributes substantial contribution for this paper.
It is impossible to conduct this experiment and prepare such kinds of
manuscript. His contribution on experimental design, data analysis and
interpretation and writing up of the manuscript was unlimited.
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