Uploaded by cduoduprah

Effect of pond fertilization on productivity of tilapia pond culture in Ghana

ISSN: 2676-2854 (Print) 2676-2862 (Online)
DOI: 10.5455/jfcom.20190722060436
Journal of Fisheries and Coastal Management 2 (2020) 56-64
Effect of pond fertilization on productivity of tilapia pond
culture in Ghana
Collins Prah Duodu 1, 2 *, , Daniel Adjei Boateng 2 , and Regina Esi Edziyie 2
Department of Marine and Fisheries Science, School of Biological Sciences, University of Ghana
Department of Fisheries and Watershed Management, Kwame Nkrumah University of Science and Technology,
Kumasi, Ghana.
*Corresponding author
E-mail: cduoduprah@gmail.com
Fish farmers have the desire to increase productivity but are constrained by high cost of formulated feeds. This
study quantified the performance and production cost of tilapia cultured in unfertilized and fertilized ponds
in six earthen ponds with sizes between 200 m2 and 300 m2. All ponds were stocked with all-male Nile tilapia
(Oreochromis niloticus) fingerlings (average size = 25.4±0.56 g) at 2 individuals per m2 and fed at 3% of their
body weight for the unfertilized and fertilized ponds, respectively. The results showed a comparable mean
weight gain of 204.2±36.3 g and 202.9±23.8 g for the unfertilized and fertilized ponds, respectively. Similar
results were obtained for the specific growth rate (1.0±0.4; 1.1±0.4 %day-1), feed conversion ratio (1.1±0.2;
1.2±0.3) and feed intake with values of 0.7±0.5; 0.7±0.3 for unfertilized and fertilized ponds respectively.
Total cost of production for the unfertilized treatment was USD$ 832.00 (273.97±86.48) and the unfertilized
treatment amounted to USD$ 834.72 (274.88±60.34). A profit of USD$ 319.42 (106.48±90.99) and USD$
353.05 (120.59±98.09) were realized for the unfertilized and fertilized treatments, respectively. The results of
this study indicate that farmers could increase their pond’s productivity and profit through pond fertilization
and feeding with formulated feed.
Keywords: Inorganic fertilizer, Tilapia, Pond culture, Cost-effectiveness.
1.0 Introduction
In the past decade, fish nutrition has
advanced dramatically with the development
of commercial diets that promote optimal
fish growth and health. Moreover, fish feed
represents 50-70% of the production costs of
commercial fish farming (El-Sayed, 2004). In
Ghana, the use of complete commercial feed
especially by pond farmers is limited due to the
relatively higher cost of the feed in comparison
to supplementary feeds. Consequently, pond
farmers rely on low quality agro-by-products
like rice bran, wheat bran, and groundnut
peels etc. which are nutritionally incomplete.
These by-products are lacking in essential
amino acids such as methionine, lysine and
contains anti-nutritional factors such as
© 2020. J. Fish Coast. Mgt., Department of Fisheries and Aquatic
Sciences, University of Cape Coast. All rights reserved.
tannins/saponins (Tacon 1993; Annongu et
al., 1996; Francis et al., 2001; Ogunji, 2004)
which interfere with food utilisation and affect
health and production of animals (Makkar,
1993). Farmers have the desire to increase
productivity but are constrained by the high
cost of formulated feeds.
In pond culture, formulated feed utilization
can be optimized while maximizing gains from
natural food sources. Shroeder (1980) reported
that natural food could account for as much as
50-70% of total available food for tilapia in pond
culture even when a complete diet is provided.
Studies by Green (1992) and Diana et al. (1994)
showed that the growth performance of tilapia
in ponds could be significantly improved
by use of organic and inorganic fertilizers
with formulated feeds at reduced ration.
Moreover, inorganic fertilizers are reported to
be hygienic and tend to produce better water
Duodu et al. /Journal of Fisheries and Coastal Management 2 (2020) 56-64
and fish quality (Diana, 2012). Shang (1990)
indicated that even though economic research
is primarily important, it is often neglected by
aquaculturists. This could be associated with
most tilapia pond farmers in Ghana who keep
little or no economic records on their farm’s
operations and complain of poor returns
and do not see aquaculture as a lucrative
business. Yi and Diana (2008) suggested that
economic analysis to determine efficiency of
resource allocation and management practices
is essential in aquaculture. This study was
conducted to quantify the performance of fish
cultured in fertilized and unfertilized ponds
and fed the recommended ration of formulated
feed (El-Dahhar, 2000) and to assess the costeffectiveness of using inorganic fertilizers to
improve productivity of tilapia raised in ponds
by use of a simple farm enterprise budget.
limed at a rate of 1 kg agriculture lime per 10
m2. The pond dykes and surroundings were
cleared to deny predators of hiding places. The
ponds were then filled with water and allowed
to stand for a day to enable suspended particles
to settle before stocking. The study design
followed the completely randomized design
(CRD) where two treatments thus, fertilized
and unfertilized treatments were assigned
randomly in triplicate groups to the ponds.
2.0 Materials and Methods
Ponds were fertilized with Mono
Ammonium Phosphate (MAP) at 2 g m-2 and
Urea at 3 g m-2 weekly; strictly according to the
phytoplankton abundance, using Secchi-disk
depth (25-30 cm) as a proxy for phytoplankton
abundance due to its strong relationship with
chlorophyll-a (Kordi et al., 2012). Fish were
fed a commercial floating feed (Raanan) at
rates of 3-1.5% of their body weight for the
two treatments. During the 1st eight weeks of
the trial, fish were given a feed that contained
2.1 Study area and pond preparation
The study was conducted for 233 days at the
fish farm of the Faculty of Renewable Natural
Resources, Kwame Nkrumah University of
Science and Technology (KNUST), in Kumasi
(longitude 6.35°-6.40° and latitude 1.3°-1.35°)
in the Ashanti Region, Ghana. Six ponds
ranging between 200–300 m2 (Figure 1) were
used. Ponds were drained, dried, de-silted and
2.2 Fingerlings and stocking
All-male tilapia (Oreochromis niloticus)
fingerlings were initially obtained at a size of 2 g
from Crystal Lake Limited, Dodi-Asantekrom,
Eastern Region, Ghana. Fish were nursed to
an approximate size of 25 g before they were
stocked at 2 fish m-2 (Anani et al., 2017).
2.3 Fertilizer application and feeding
Figure 1: Aerial view of the study site with experimental ponds (enclosed in red border lines).
Effect of pond fertilization on productivity of tilapia pond culture in Ghana
33% dietary protein (2.5 mm pellet diameter),
thereafter they were fed with a 30% dietary
protein feed (4.5 mm pellet diameters) as per
the standard practice by local fish farmers to
meet the nutritional needs of tilapia at the
different life stages. Fish were fed to apparent
satiation and the feed rate for the next feeding
determined from previous feed fed. Feeding
was done twice daily between 9-10 am and
between 3-4 pm. Feeding levels were adjusted
after each monthly sampling. However, fish
were not fed on the day they were sampled to
allow recovery from stress due to seining and
2.4 Fish sampling and water quality
Fifty fish in each pond were sampled by
seining through the ponds from one vertical
end to the other. The bulk weight of the catch
was determined with a weighing balance
(MITSUBA model: MB-320) and the average
weight calculated to monitor growth and
adjust the feed levels. The growth performance
and feed utilization of fish from each pond was
determined by conventional methods (Agbo et
al., 2011) as follows:
The net yield of fish was reported as the
(TDS), conductivity, temperature, and pH
were collected in situ using the Hanna (HI
9828) multi parameter probe. Secchi readings
were taken in each pond using a Secchi-disk
every two weeks after fertilization.
2.5 Fish sales and cost-benefit analyses
Fish were harvested and sold at the premises
of the Faculty of Renewable Natural Resources,
KNUST. Fish were put into two categories as
large (260-330g) and small (200-250g) and
sold per piece in accordance with the local
market price. All monetary values are quoted
in the United States Dollars (USD $) as at the
time of the research. According to the Bank of
Ghana, the average Interbank FX Rate between
January 2013 and September 2013 was USD
$ 1.00 = GHC 1.9421. The effectiveness and
efficiency of the treatments were ascertained by
developing an enterprise budget that compared
the cost of production basically in terms of cost
of fingerlings, fertilizer used, quantity of feed
given and labour, and the revenue that accrued
from fish sales. Prices of items were based on
the prevailing local market price.
Profit index was calculated as
Where, net profit was considered as the profit accrued
after all production (variable) cost has been accounted
for whereas the total investment determined as only the
variable cost incurred.
2.6 Statistical analyses
actual biomass of fish that was harvested from
the ponds at the end of the trial period.
Water samples were collected fortnightly to
determine the concentration of Chlorophyll-a
according to the standard method described
in HMSO (1983). Data for dissolved oxygen
(DO) concentration, total dissolved solids
Potential differences in the final weights,
specific growth rates, weight gain, feed
conversion ratios, feed intake, survival rates,
gross yield, and net yield of the fish cultured
under the two feeding treatments were
evaluated using student’s t-test at p < 0.05.
The same statistical procedure was used to
assess potential differences in each of the
Duodu et al. /Journal of Fisheries and Coastal Management 2 (2020) 56-64
physicochemical variables observed in the
ponds used for the two treatments. All analyses
were done with GraphPad Prism version 5.01
Software for Windows.
3.0 Results
3.1 Growth performance and feed utilization of Nile
Growth performance was assessed by the
following indicators: final weight (FW), weight
gain (WG), specific growth weight (SGR),
survival rate (SR), gross yield (GY) and net
yield (NY) as indicated in Table 1. Generally,
there was a steady increase in fish weight
from January to March, but growth slowed
slightly between March and April (Figure 2).
Thereafter, a gradual increase in growth was
recorded from May till the end of the growout period in both treatments. The SR was
similar in both treatments. Nonetheless, fish
weight gain was 5.7% more in the fertilized
ponds compared to the unfertilized ponds. Yet,
SGR in both treatments were similar. There
were no significant differences between the
two treatments for all the growth parameters
assessed. The FCR was similar (Table 2),
whereas the daily feed intake per fish revealed
very low intake for both treatments although
the average temperature in the treatment ponds
(26.5–28.4 °C) were close to the recommended
temperature (27.0 °C) (Pandit and Nakamura,
2010) for optimum growth (Table 3). Generally,
all the parameters assessed for feed utilization
Table 1 - Growth performance (average ± standard deviation) of
Nile tilapia fed in unfertilized and fertilized earthen ponds for
233 days.
Initial weight (g)
25.0 ± 8.0
25.8 ± 8.5
Final weight (g)
229.1 ± 33.5
228.7 ± 23.3
Weight gain (g)
204.2 ± 27.9
202.9 ± 24.0
Specific growth rate
1.02 ± 0.37
1.10 ± 0.35
Survival rate (%)
62.6 ± 20.3
Gross yield (kg/ha)
4935.17 ± 589.19
Net Yield (kg/ha)
4021.55 ± 677.61
N = 3 ponds for each treatment.
Figure 2: Growth performance of Nile tilapia fed in unfertilized
and fertilized earthen ponds.
did not show any significant difference (p <
0.05) between the two treatments.
3.2 Physicochemical parameters and chlorophyll-a
Temperature recorded over the study
period for both the unfertilized and fertilized
treatments did not show any significant
differences (p = 0.775 at df = 10, t-value =
0.2931). Ponds that received no fertilization
recorded mean temperature of 27.8 ± 0.3°C
and that for the fertilized ponds was 28.0 ± 0.3
°C over the study period (Table 4). Similarly,
there was no significant difference (p = 0.698
at df = 10, t-value = 0.3984) in pH between
the two treatments with both recording very
narrow variations. On the other hand, DO
concentrations recorded over the study period
varied widely ranging from 1.8 to 7.7 mgl-1
for the unfertilized treatment and from 2.1
Table 2 - Feed utilization (average ± standard deviation) of Nile
tilapia fed in unfertilized and fertilized earthen ponds for 233
Feeding Treatment
Feed conversion ratio
1.1 ± 0.2
1.2 ± 0.3
63.9 ± 13.0
Feed efficiency ratio
1.4 ± 0.9
0.9 ± 0.2
5077.08 ± 401.76
Feed fed (kg)
116.4 ± 53.0
112.0 ± 27.6
4303.27 ± 408.43
Feed intake (g/fish)
0.7 ± 0.5
0.7 ± 0.3
N = 3 ponds for each treatment.
Effect of pond fertilization on productivity of tilapia pond culture in Ghana
Table 3 – Observed daily feed rate and temperature for tilapia
cultured in unfertilized and fertilized ponds.
of fish
Daily feed/
fish (g)
0.78 ± 0.00
27.12 ± 0.00
0.73 ± 0.11
28.38 ± 0.20
0.89 ± 0.11
28.18 ± 0.31
0.71 ± 0.37
28.36 ± 0.44
1.24 ± 1.08
28.15 ± 0.32
1.37 ± 0.49
26.94 ± 1.23
1.67 ± 0.58
27.10 ± 0.41
1.63 ± 0.48
26.45 ± 0.56
0.19 ± 0.00
27.82 ± 0.00
0.78 ± 0.18
28.60 ± 0.30
0.72 ± 0.14
28.05 ± 0.32
0.65 ± 0.20
28.34 ± 0.67
1.25 ± 0.46
28.23 ± 0.29
1.65 ± 0.43
26.83 ± 1.12
1.80 ± 0.18
27.20 ± 0.87
1.63 ± 0.48
26.20 ± 0.25
* day of stocking
to 6.2 mgl-1 for the fertilized treatment (Table
4), however, with no significant differences
between treatments means (p = 0.674 at df = 10,
t-value = 0.4328). Conductivity of the fertilized
ponds was rather 16% higher compared to
the unfertilized ponds. Secchi depth showed
wide variations in both treatments and was
approximately 25% clearer in the fertilized
ponds than the unfertilized ponds (Table 4).
Chlorophyll-a concentration was highest (p
= < 0.0001 at df = 10, t-value = 6.348) and
almost double in the unfertilized ponds than
the fertilized treatment. The fertilized ponds
however, recorded lower concentrations with a
mean of 1374 ± 239 µgl-1 (Table 4).
3.3 Cost of production
The costs of all inputs as well as the prices
of fish were based on local market prices in
Kumasi. The economics of fish production
in this study indicated that the total cost of
production was slightly higher (USD 834.73)
for the fertilized treatment compared to the
unfertilized treatment (USD 832.00). The total
cost of pond preparation was marginally higher
in the fertilized ponds than the unfertilized
treatment. At harvest, small size (200-250 g)
fish were sold at USD 1.03 and the large (> 250
g) at USD 1.29 per piece as indicated in Table 5.
This resulted in a higher profit for the fertilized
Table 4 – Physicochemical parameters and Chlorophyll-a concentration in unfertilized and fertilized tilapia earthen ponds during the
study period.
Temperature (°C)
Mean ± Standard Deviation
27.9 ± 0.3
28 ± 0.3
27.0 - 28.4
26.8 - 28.6
8.1 ± 0.3
7.9 ± 0.3
7.0 - 9.0
6.9 - 8.7
Dissolved Oxygen (mg/l)
4.8 ± 0.8
4.4 ± 0.6
1.8 - 7.7
2.1 - 6.2
Conductivity (µs/cm)
150 ± 21
174 ± 17
102 - 250
123 - 239
Total Dissolved Solids (mg/l)
74 ± 9
86 ± 9
51- 118
62 - 119
Secchi Depth (cm)
12.6 ± 1.6
15.7 ± 1.5
11.2 - 19.2
10.8 - 20.5
2286 ± 258
1374 ± 239
1843 - 2574
1008 - 1607
Chlorophyll-a (µg/L)
N= 8; monthly averages from the three replicates for each treatment.
Duodu et al. /Journal of Fisheries and Coastal Management 2 (2020) 56-64
Table 5 - Enterprise budget for unfertilized and fertilized feed treatments for one production cycle in Ghana. Cost and price information is
in United States Dollars (USD) based on an exchange rate of USD$ 1 = GHC 1.9421 provided by the Bank of Ghana in September 2013
Unfertilised ponds
Fertilised ponds
ITEM (Unit)
Fingerlings (/piece)
Pond Rent (/month)
Subtotal A
Juvenile fish (2.5mm) (kg)
Growout fish (4.5mm) (kg)
Growout fish (6.0mm) (kg)
Subtotal B
Pond Preparation and treatment
Lime (kg)
MAP (kg)
UREA (kg)
Fuel for filling pond with water
Labour (per day)
Subtotal C
Total production cost (A+B+C)
Revenue from fish sales
Large fish (per piece) (D)
Small fish (per piece) (E)
Reproduction (kg)*
Total revenue
Profit index
Economy of weight gain (USD.kg-1)
Return on investment (ROI) (%)
*Quantity presented in kilograms (kg)
Effect of pond fertilization on productivity of tilapia pond culture in Ghana
4. Discussion
4.1 Growth performance of Nile tilapia
Survival rate in this experiment was
generally low but was higher in the fertilized
treatment compared to the unfertilized
treatment. This is contrary to observations
from Diana et al. (1994), who recorded a lower
survival in the feed and fertilizer treatment
in their experiment. The lower survival rate
in this experiment could not be linked to the
application of the treatments, but instead to
the invasion of predators such as snakes, birds
and frogs (Figure 3) which might have preyed
on the fish especially at the early stages of the
experiment. According to Diana et al. (1994)
the presence of predators could affect the yield
of fish resulting in variable survival among
treatment replicates.
Figure 3: Predators observed; (a) captured frog with fish in mouth
during sampling (b) a bird trapped by predator net overlaying one
of the experimental ponds.
It was expected that fish that received the
unfertilized treatment would perform better
than those receiving the fertilized treatment;
however, that was not the case. The growth
in the fertilized treatment could be attributed
to the fishes’ ability to utilize the abundant
natural food available in the ponds. The
unfertilized ponds rather responded poorly to
the feed which resulted in many uneaten feeds
observed at the surface of the pond water 30
minutes after feeding. A possible reason for
the poor response could be attributed to the
fish feeding on natural feed sources available
in the pond as the unfertilized ponds had
abundant phytoplankton levels as a result of
continuous fertilization from uneaten feed,
although, that was an unintended consequence
(Table 4). Mud accumulation at the bottom of
ponds as a result of seining during sampling
led to a decrease in pond depth, dense growth
of duckweed coupled with lower water levels
during the dry season might have accounted
for the poor response of fish to feed. The
decline in tilapia growth in both treatments
in April could be linked to high temperatures
which made the pond water warmer thus, the
fishes’ reluctance to swim up to the surface to
feed. Low DO concentration at the peak of the
dry season might have also caused low fish
metabolism thereby depressing growth (Brett,
1979). This resulted in a lower average growth
rate (1.1 ± 0.3g/day) of tilapia observed in this
study compared to that reported (2.0-3.1g/
day) by other studies (Green, 1992; Diana et
al., 1994).
4.2 Feed utilization and water quality
The similarity in FCR of the treatments
confirms the report by Hepher and Pruginin
(1982) and Diana et al. (1994), who recorded
similar FCR for ponds receiving feed only or
feed and fertilizer input in their study. The
fertilizer treatment in this study had an FCR
near one suggesting that the fish benefited
from natural food available in the ponds which
was boosted by fertilization. Shroeder (1980)
reported that natural food could account for
as much as 50-70% of total available food for
tilapia in pond culture even when complete
diet is provided. Other authors like Green
(1992), emphasized that natural productivity
influenced by pond fertilization was enough
to promote accelerated fish growth in tilapia
pond culture.
Certainly, one might expect the total
quantity of feed applied to be similar in
both treatments, however, feed utilized by
the fertilized ponds treatment was slightly
more than the unfertilized. This could be
attributed to the fact that the quantity of feed
given to fish in the treatments was adjusted
based on the average body weight after the
monthly sampling. Moreover, fish were fed to
satiation and so the poor response by the fish
that received the unfertilized pond treatment
ended up with less feed consumed. This poor
Duodu et al. /Journal of Fisheries and Coastal Management 2 (2020) 56-64
response may not be due to low DO levels
since the water quality was similar for the two
treatments (Table 4). A possible reason could
be the availability of natural food to the fish
indicated by the high chlorophyll-a levels in
the no fertilizer treatment hence their poor
response to the feed. One of the reasons that
could account for lower feed intake in fish is
poor water quality. However, since water quality
in this study was generally within a favourable
range for tilapia, the lower feed intake per fish
per day (Table 3) could also be linked to the
presence of other animals (predators) (Meena,
2014) that scare the fish away from the food by
attacking them during feeding.
All the water quality parameters monitored
(Table 4) were in the favourable range for tilapia
culture (Boyd, 1990) except for DO which
varied widely. Temperature of the water in
both treatments was within the optimal range
of 26-30°C (Lazur, 2007). This was expected
since all ponds were exposed to similar
environmental conditions such as sunlight
and wind (Diana et al., 1994). However,
the wider variations in DO concentrations
observed in both treatments could be a result
of the high chlorophyll-a concentration
which usually results in wider fluctuations
in DO concentration within a day. Similar
variation was also reported by Thakur et al.
(2007). Diana et al. (1994) suggested that wide
variation in DO levels could also be due to the
high oxygen demand and nutrient loading on
pond bottom which push DO levels extremely
low. The pH range (6.89 - 8.96) recorded for all
ponds in this study were similar to the range
of 6.5 to 8.5 recorded by Diana et al. (1994).
The lower visibility (Secchi readings) in the
unfertilized ponds treatment was supported by
the high chlorophyll-a levels, suggesting a high
phytoplankton abundance. The higher visibility
in the fertilized ponds treatment suggests
a high utilization of phytoplankton by the
fish. Although, natural food utilization in the
unfertilized ponds were possible, continuous
fertilization from uneaten feed contributed to
abundant algae impeding visibility. Diana et
al. (1994) reported no significant difference
in Secchi depth among treatments (fertilized
and unfertilized ponds) and attributed this
to the similar amount of light (and heat).
Chlorophyll-a concentration increased in the
first month of the study and showed a relatively
stable concentration in the last half of the study
as reported by Thakur et al. (2007). Contrary
to what was reported by Thakur et al. (2007)
who fertilized ponds throughout the culture
period and started feeding Nile tilapia from
day 80 (half way through the culture period),
fertilization plus feeding in this study recorded
lower chlorophyll-a concentration. Moreover,
significantly between the treatments. The lower
level of chlorophyll-a was an indication of the
low abundance of phytoplankton which was
probably due to the fish’s reliance and effective
grazing on the available phytoplankton.
4.3 Production Costs and Revenue
The economic analysis (Table 5) suggests
that both treatments could be profitable. This
agrees with Diana et al. (1996) who observed
that the 0.5 ad libitum and fertilization
treatment in their experiment was the most
profitable. Thakur et al. (2007) indicated that
better economic returns in fertilized tilapia
ponds could be attributed to improved growth
performance of the fish due to the presence of
natural food in ponds. The cost of production
(Table 5) was slightly higher in the fertilized
pond treatment and could be attributed to the
cost of fertilizer input. The poor feed response
by the fish fed feed without fertilization in
this study contributed to a slightly lower
quantity of feed fed. Another possible reason
was that the quantity of feed applied to both
treatments was adjusted monthly based on
fish weights determined after sampling at the
end of the previous month. Hence, the gross
revenue and profit generated after the sale of
fish did not reveal any difference between the
two treatments. Even though both treatments
made a profit, the fertilizer pond treatment
made approximately 6% more than the
unfertilized treatment. A study by Thakur et
al. (2007) which assessed the culture of tilapia
under fertilization plus feed compared to
tilapia under feed only reported an increase in
Effect of pond fertilization on productivity of tilapia pond culture in Ghana
net income for the former. Finally, only feed
input accounted for 43.7% and 42.5% (without
cost of fertilizer) to the total cost of production
for the unfertilized and fertilized treatments,
respectively. This suggests that when an efficient
fertilization and feeding regime is applied and
natural food is readily available or well utilized
by fish the amount of feed required for good
growth could reduce to 45% of the production
cost in tilapia pond farming. Overall, this study
supports the assertion by Diana et al. (1994)
and Diana et al. (1996) that fertilizing tilapia
ponds is profitable and produced higher yields
(Thakur et al., 2007).
Generally, it can be concluded that
fertilizing tilapia ponds and providing feed
administered strictly based on fish response to
feed could have beneficial effects. The addition
of inorganic fertilizer did not adversely
affect the water quality. Therefore, tilapia
pond farmers could increase their yield by
fertilizing their ponds to enhance natural food
The authors would like to thank the
Technician and the farm staff of the Department
of Fisheries and Watershed Management,
Kwame Nkrumah University of Science and
Technology for their assistance during the
monthly fish sampling periods.
Anani, F.A., Nunoo, F.K.E., Steiner-Asiedu, M., Nortey, T.N.N.,
& Agbo, N.W. (2017). Evaluation of Farm-made and
Commercial Tilapia Diets for Small-scale Hapa Production
of Nile Tilapia (Oreochromis niloticus L.) in Ghana. Journal of
Applied Life Sciences International, 10(3), 1-12.
Annongu, A.A., Termeulen, U., & Atteh, J.O. (1996). Response
of broilers to dietary treated and untreated Shea butter cake
supplemented with molasses. Landbauforschung Volkenrode,
Sonderheft, 169, 295 - 300.
Boyd, C.E. (1990). Water quality in ponds for aquaculture. Alabama
Agriculture Experiment Station, Auburn University, Alabama,
Brett, J.R. (1979). Environmental factors and growth. In W.S. Hoar,
D.J. Randall & J.R. Brett (Eds.), Fish physiology (pp. 599-677),
VIII. Academic Press, New York, USA,.
Diana, J.S. (2012). Some principles of pond fertilization for Nile
tilapia using organic and inorganic inputs. In C.C. Mischke
(Ed.), Aquaculture Pond Fertilization: Impacts of Nutrient
Input on Production (pp 163-177). 1st Edition. John Wiley &
Sons, Inc.
Diana, J.S., Lin C.K., & Jaiyen, K. (1994). Supplemental feeding of
tilapia in fertilized ponds. Journal of the World Aquaculture
Society, 25, 497-506.
Diana, J.S., Lin, C.K., & Yang, Y. (1996). Timing of supplemental
feeding for tilapia production. Journal of the World
Aquaculture Society 27:410- 419.
El-Dahhar, A.A. (2000). Developing a feeding guide for Nile tilapia
Oreochromis niloticus based on dietary protein levels fed.
Conference of Social and Agriculture development in Sinai.
El-Sayed, A.F.M. (2004). Protein nutrition of farmed tilapia:
Searching for unconventional sources. In R.B. Bolivar, G.C.
Mair, & K. Fitzsimmons (Eds.), ‘New Dimensions on farmed
tilapia’ Proceedings of the Sixth International Symposium on
Tilapia in Aquaculture, pp. 364-378. Manila, Philippines: ISTA
Francis, G., Makkar, H.P.S. & Becker, K. (2001). Anti-nutritional
factors present in plant-derived alternate fish feed ingredients
and their effects in fish. Aquaculture, 199, 197-227.
Green, B.W. (1992). Substitution of organic manure for pelleted
feed in tilapia production. Aquaculture, 101, 213-222.
Hepher, B., & Pruginin, Y. (1982). Tilapia culture in ponds under
controlled conditions. In Pullen, R.S.V. & Lowe-McConnell,
R.H. (Eds.). The biology and culture of tilapias (pp 185204). International Center for Living Aquatic Resources
Management, Manila, Philippines.
HMSO (1983). The Determination of Chlorophyll-a in Aquatic
Environments. HMSO Publications, London.
Kordi, H., Hoseini, S.A., Sudagar, M., & Alimohammadi, A.A.
(2012). Correlation of Chlorophyll-a with Secchi disk depth
and water turbidity in aquaculture reservoirs. A case study on
Mohammadabad Reservoirs, Gorgan, Iran. World Journal of
Fish and Marine Sciences, 4, 340-343.
Lazur, A. (2007). Good Aquacultural Practices Manual: Grow-out
Pond and Water Quality Management.
Makkar, H.P.S. (1993). Anti-nutritional factors in foods for
livestock. In Gill, M., Owen, E., Pollot, G.E. & Lawrence,
T.L.J. (Eds.), Animal Production in Developing Countries (pp.
69–85). British Society of Animal Production. No. 16.
Meena, D.K. (2014). Regulation and perspective of feed intake in
fish. http://aquafind.com/articles/Feed-Intake-In-Fish.php.
Accessed on 12/03/2015.
Ogunji, J.O. (2004). Alternative protein sources in diets for farmed
tilapia. CABI International Nutrition Abstracts and Reviews, 9,
Pandit, N.P., & Nakamura, M. (2010). Effect of high temperature
on survival, growth and feed conversion ratio of Nile tilapia,
Oreochromis niloticus. Our Nature, 8(11), 219-224.
Shang, Y.C. (1990). Aquaculture economic analysis: An
introduction. World Aquaculture Society, Baton Rouge, pp
Shroeder, G.L. (1980). The breakdown of feeding niches in fish
ponds under conditions of severe competition. Bamidgeh, 32,
Tacon, A.G.J. (1993). Supplementary feeding in semi-intensive
aquaculture systems. In New, M.B., Tacon, A.G.J. & Csavas, I.
(Eds.), Farm Made Aquafeeds. Proceedings of the FAO/AADCP
(Bangkok, Thailand), Rome,pp. 61-74.
Thakur, D.P., Yi, Y., Diana, J.S., & Lin, C.K. (2007). Effects of
fertilization and feeding strategy on water quality, growth
performance, nutrient utilization and economic return in
Nile tilapia. CRSP Research Report 04-A13, http://citeseerx.
Yi, Y., & Diana, J.S. (2008). Strategies for Nile tilapia (Oreochromis
niloticus) pond culture. Proceedings of the 8th International
Symposium on Tilapia in Aquaculture, Cairo, Egypt, 12-14 pp.
Received 12 February 2019
Accepted 06 October 2020
First Online 11 October 2020
Published Online 18 May 2021