ArticlePDF Available

Effects of over stocking on the growth rate of Clarias gariepinus

Authors:

Abstract

The African catfish (Clarias gariepinus) were reared at four different stocking densities in a circular plastic bowls to evaluate the effects of over stocking on the growth rate of Clarias gariepinus. 140 fish were stocked at 10, 20, 30 and 40 with a mean of 8.5, 8.66, 9.2 and 9.15 respectively. The growth trial lasted for 92 days (June to August). The final mean weight of fish stocked at densities 10, 20, 30 and 40 were 153.1, 121.5, 96.6 and 68.6 (g) fish were with 10% body weight between the hour of 8.00 to 9.00am and 5.00pm to 6.00pm. Feed not consumed are siphoned out to avoid contamination of water which will be toxic to the fish. The corresponding mean values of specific growth rate were 3.05, 2.80, 2.62, and 2.26. The feed conversion ratio (FCR) was 5.91, 5.45, 5.14 and 4.76 and cumulative survival rates were 99.86, 99.65,96 .66 and 92.5%. The temperature range from 26.5 to 30.5°C. The pH range from 6.9 to ± 0.36 to 7.25 ± 0.22. The Dissolved oxygen (DO) was 2.65mg/l to 5.41 mg/l. The result revealed that over stocking had a significant effect on the growth rates of Clarias gariepinus. Fish held at the highest stocking density of 40 exhibited the lowest growth and survival rate.
Journal of Animal Science and Veterinary Medicine
Volume 2. Page 84-95. Published 23rd May, 2017
ISSN: 2536-7099. Article Number: JASVM-02.05.17-056
www.integrityresjournals.org/jasvm/index.html
Full Length Research
Effects of over stocking on the growth rate of Clarias
gariepinus
Ojonugwa, E. B. and Solomon, R. J.*
Department of Biological Sciences, Faculty of Science, University of Abuja, Abuja- Nigeria.
*Corresponding author. Email: johnsol2004@yahoo.com
Copyright © 2017 Ojonugwa and Solomon. This article remains permanently open access under the terms of the Creative Commons Attribution
License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Received 2nd May, 2017; Accepted 19th May, 2017
ABSTRACT: The African catfish (Clarias gariepinus) were reared at four different stocking densities in a circular plastic
bowls to evaluate the effects of over stocking on the growth rate of Clarias gariepinus. 140 fish were stocked at 10, 20,
30 and 40 with a mean of 8.5, 8.66, 9.2 and 9.15 respectively. The growth trial lasted for 92 days (June to August). The
final mean weight of fish stocked at densities 10, 20, 30 and 40 were 153.1, 121.5, 96.6 and 68.6 (g) fish were with 10%
body weight between the hour of 8.00 to 9.00am and 5.00pm to 6.00pm. Feed not consumed are siphoned out to avoid
contamination of water which will be toxic to the fish. The corresponding mean values of specific growth rate were 3.05,
2.80, 2.62, and 2.26. The feed conversion ratio (FCR) was 5.91, 5.45, 5.14 and 4.76 and cumulative survival rates were
99.86, 99.65,96 .66 and 92.5%. The temperature range from 26.5 to 30.5°C. The pH range from 6.9 to ± 0.36 to 7.25 ±
0.22. The Dissolved oxygen (DO) was 2.65mg/l to 5.41 mg/l. The result revealed that over stocking had a significant
effect on the growth rates of Clarias gariepinus. Fish held at the highest stocking density of 40 exhibited the lowest
growth and survival rate.
Key words: African catfish, over stocking, growth rate.
INTRODUCTION
Aquaculture practices are still in the extensive and semi
intensive in Nigeria (Adikwu, 1999) and recently intensive
re-circulatory systems (Bolorunduro, 2006). Data on
domestic fish production in Nigeria has shown a
downward decline over the years, 1982 (920, 484), 1990
(315,000) and 1996 (200, 171) metric tons as reported by
(FDF, 1990; FOS, 1997). In order to sustain the current
average domestic production of 615,507 metric tons per
annum, an effective delivery system has to be put in
place (FDF, 2007). Nigeria is amongst the largest
consumer of fish in Africa (FAO, 1999); its total available
land for aquaculture development according to fisheries
statistics of Nigeria is about 1.7 million hectares and
existing pond area under cultivation is about 60,000
hactares with a domestic production of merely 0.62
million metric tons while it has an aquaculture potential of
producing about 2.5 million tons. Nigeria’s current
domestic fish production from aquaculture is only about
85, 087 tones and consumption was estimated to be over
one million metric tons, in order to reduce importation of
fish in Nigeria, there is need to develop local domestic
fish production.
Clarias gariepinus is a highly appreciated fish in Nigeria
due to its favorable food conversion ratio, resistance to
disease, low technology farming system, excellent food
meat quality, possibility for high stocking density and can
tolerate wide ranges of environmental conditions
(Fagbenro et al., 2003) and also they can grow to a large
size of over 10kg (Reed et al., 1967; Olaosebikan and
Raji, 1999) which are attractive to consumers. Thus,
Clarias gariepinus was chosen for this study because of
its ready availability, economic and ecological advantages.
Environmental stress is an important factor responsible
for limiting fish performance under aquaculture
conditions. When fish are subjected to adverse environ-
mental conditions, some endocrine and physiological
alteration occur, often resulting in changes in ability of the
fish to survive, grow and reproduce (Barton and Iwama,
1991) over stocking is a common chronic stressor in
aquaculture that can induce a prolonged elevation of
Cortisol levls which may cause damaging consequences,
and suppressed growth (Rowland et al., 2006). This
effect has been attributed to factors such as decreased
food consumption. The high stocking density (over
stocking) also imposes increased energy demands that
require changes of gluconeogenic and glucolytic activities
under such conditions, food consumption is reduced. The
extra expenditure energy has to be met by the reserve,
resulting in reduced growth (Rowland et al., 2006). Over
stocking is a common aquaculture practice used to
manage water usage or increase fish stocking density
(Baras and Lagardere, 1995). However, the use of high
stocking density as a technique to maximize water usage
and thus increase stock production has also been shown
to have adverse effect on growth. In many cultured fish
species, growth has indirect relationship to stocking
density and this observation is mainly attributed to social
interaction (Holm et al., 1990; Haylor 1991; Ma et.al.,
2006). Social interactions as a result of competition for
food and/or space can negatively affect fish growth. On
the other hand, the fish price is influenced by the market
requirements such as size and production, which
depends on their growth.
According to Brummet, (2000) when the amount of fish
stocks exceeds the carrying capacity of the water supply,
and the condition of the fish deteriorates then mortality
will increase due to rapid growth of protozoa and
bacterial diseases and parasites. Therefore by
establishing the relationship between dietary protein level
and over stocking, stress monitoring of fish stocks and
prediction on their growth rate need will be possible and
enhanced. With global population expansion, the demand
for fish is steadily increasing and natural fish population
have declined during the last decade due to
environmental degradation and overfishing. This has
resulted in an increasing effort in the technology for more
domestic production. A lot of people have gone into the
fish farming at both subsistence and commercial level in
north-central Nigeria; however , there has been low
capacity production due to problems of knowing the right
size of fish to stock, stocking at too high density (over
stocking) and under-stocking of fish (Edward and
Demaine, 1988). A lot of farmers have been discouraged
by incidence of high mortality in the present day practice
in north-central Nigeria .plastic container used in culturing
fish is not new in Nigeria , the problem is that the practice
has remained at experimental level for over two decades
(Okorie,2003). There have been different researches
concerning different species of catfish, all over the world
for aquaculture because of its high potentiality and
preference. Stocking at best density in order to avoid
over stocking still attract attention of researchers because
factors are aimed at yielding a higher profit for the
farmers and getting good quality fish at a reasonably
Ojonugwa and Solomon 85
short period of time.
The growth of Clarias species depends upon stocking
density, dietary, protein quality, energy content of feed,
physiological status (age, sex) environmental variables,
farming conditions and food availability are some of the
main factors that affects fish growth (Lovell, 1989). In
terms of the fish production in plastic containers, over
stocking (high stocking density) which is related to the
volume of water or surface area per fish is an important
factor. Increase in stocking density (over stocking) results
in increasing stress, which leads to higher energy
requirements, causing a reduction in growth rate and
food utilization. Contrarily, in case of low stocking
densities fish may not form shoals and feel comfortable.
Consequently, identifying the optimum stocking density
for a species is a critical factor not only for designing an
efficient culture system (Leatherland and Cho, 1985), but
also for optimum husbandry practices. Controlling the fish
size and production are the two importance task to meet
the market demands as price of fish is determined by the
market demand of supply (Size and production) and that
in turn depends on their growth rate. Over stocking (High
stocking density) to produce more fish which increase
fish intensification may not be the problem of space
shortage.
Biology of Clarias gariepinus
Clarias gariepinus is a member of the family clarridae.
They occur naturally in south East Asia and in Africa and
are sometimes called Africa catfish or mudfish. Clarias
gariepinus is well appreciated in many Africa countries
(De gram et al., 1996). The clariids exhibits many
qualities which makes them suitable for culturing. They
have a high fecundity, faster growth rate, disease
resistance can withstand handling stress as well as been
highly palatable (Eroudu et al., 1993; Nwandukwe, 1993).
They are very adaptive to extreme environmental
conditions and can withstand low oxygen level in the
range of 6.5 to 8.0 (Huissman and Ritcher, 1987;
Fabgenro and Sydenham, 1988). They are able to live in
turbid water and tolerate temperature of 8°-35°c. the
optimal temperature for growth is 28°-30°C (Teugel,
1986) Clarias gariepinus has long based rayed dorsal fin
(reed et al., 1967) without an adipose tissue, two pairs of
nasal and maxillary barbles on its dorso ventrally
flattened head, elongated body with fairly long dorsal and
anal fins and also smallish eyes. This species can attain
length of up to 1.7m including the tail and can weigh 59kg
when fully grow their color ranges from dark grey to black
dorsally and cream coloured ventrally (Skelton, 1993). It
comprises of species such as Clarias anguillaris, Clarias
gariepinus, Clarias lazera and Clarias mossambicus
(Teugels, 1982). The Africa catfish are omnivores (Reed
et al., 1967) feeding on a large variety of plant and
86 J. Anim. Sci. Vet. Med.
animals like weed, planktons, small insects, small fish,
crustaceans, worms etc. (Bakare, 1968) but they have
high tendency towards been a carnivores as adult.
Catfish are therefore said to be an opportunistic feeder,
feeding on virtually everything that come their way.
Stocking density and culture
Over stocking (high stocking density) is one of the main
factors determining the growth rate of fish (Engle and
Valderama, 2001; Rahman et al., 2005) and the final
biomass harvesters (Boujard et al., 2002). Environmental
variables, farming conditions and food availability are
other factors that can affect fish growth. in terms of the
fish production in plastic container, over stocking
(stocking density) which is related to the volume of water
or surface area per fish is an important factor. Increase in
stocking density that is over stocking result in increasing
stress, which leads to higher energy requirements
causing a reduction in the growth rate and food utilization
(Aksungur et al., 2007).
Contrarily, in case of low stocking densities fish may
not form shoals or group together and feel comfortable.
Consequently, identifying the optimum stocking density
for a species is a critical factor not only for designing an
efficient culture system (Leatherland and Cho, 1985) but
also for optimum husbandry practices. Controlling the fish
size and production are two important tasks to meet the
market demands. increase in stocking density (over
stocking) to produce more fish which increase fish
intensification may not be the best way of dealing with
problem of space shortage (Aksungur et al., 2007). In
many cultured fish species, growth is inversely related to
stocking density and this is mainly attributed to social
interactions and fool (Huang and Chiu, 1997; Haylor,
1991; Bjorensson, 1994; Irwin et al., 1999; Ma et al.,
2006). Social interaction through competition for food or
space can negatively affects fish growth while the price of
fish is determined by market demand of supply (size and
production) which in turn depends on their growth.
Paspt et al. (1992) suggested that in intensive
aquaculture the stocking density is an important indicator
that determines the economic viability of the production
system. In intensive larvae and fry culture, several factors
influence survival welfare, growth and production for
example feeding (Kerdchwen, 1992; El-sayed, 2002),
stocking density (Rahman et al., 2005; Schram et al.,
2004).
The effects of over stocking on the growth rate and
survival have been studied on some African catfishes
such as Clarias gariepinus (Haylor, 1992) and
Heterbrancus longifilis (Ewa-oboho and Enyenihi, 1999;
Coulibaly et al., 2007). The effects of over stocking on
tilapia production as reported by Otubusin and Opeloye,
(1985) in floating bamboo-net cages in Kigera III reservoir
New Bussa, Nigeria shows that fish growth generally
decreased with an increase in stocking density. The slow
growth rate of the fish observed in the study may be
attributed to low productivity of the Kigera III reservoir.
Muthukumarana et al. (1985) carried out an experiment
using sarotherodon niloticus in cages (at three stocking
densities; 400, 600 and 800m3) fed varying crude protein
levels for a period of four months; it was observed from
his result that there was no weight gains and feed
conversion ratio between stocking densities for a
particular dietary crude protein level. (Osotero et al.,
2007) revealed that over stocking has an inverse
relationship with level of protein intake which affects
weight and growth of fish (Clarias gariepinus). Growth is
the manifestation of the net outcome of energy gains and
losses within a framework of abiotic and biotic conditions.
In fact, under crowded conditions at higher stocking
densities, fish suffer stress as a result of aggressive
feeding interaction and eat less, resulting in growth
retardation (Bjoernsson, 1994) space is a factor which
can be used to determine the fish growth rate in
aquaculture (Otubusi, 2000).
Nutritional requirement
Protein requirement
Dietary protein requirement of Africa catfish have been
reported by several authors; Fagbenro et al. (1992)
reported 42.5% dietary protein requirement for H.
longfilis. In Clarias gariepinus, the protein requirement of
fingerling, juveniles and adult fish varies. For instance,
juveniles and fingerlings require more protein compared
to the adult (Halver, 1978) reported that the gross protein
requirements are highest in initial feeding and that it
decrease as fish increase in size. Machiels and Haenke,
(1986), Ayinla, (1988) and Degani et al. (1989) concluded
that Clarias gariepinus brood stock requires about 40%
crude protein for Clarias anguiclarias and (Fagbenro et
al., 1992) recommended 40-42.5% for Heterancus
bidorsalis. The quality of protein in any feed stuff is
principal influenced by its amino acid composition (Ayinla,
1991) and this is turn induces its digestibility in the diet.
Digestibility of some amino acids varies amongst
ingredients. Fish utilizes both plant and animal proteins
although the latter is more nutritionally better. The more
closely the dietary protein meets. The qualitative
requirement of indispensable amino acid by the fish, the
greater its utilization, for cultured fish try to grow at a
maximum rate, it must have a diet in which have its
digestible feed ingredient consist of balanced protein
(indispensable amino acid). Ayinla (1991), stated that
deficiency in any of these ten essential amino acids will
cause reduced appetite, reduced growth rate, disease or
even death in fish. The ten indispensable amino acid
needed for growth are Arginine, Histidine, Isoleuline,
Leucine, Lysine, Methionine, Phenylalanne, Valine,
Threonine and tryptophan (NRC, 1993). Fagbenro et al.
(2000) reported that the estimated essential amino acid
requirements in (g/kg protein) for Clarias gariepinus as
argentine (445), Histindine (21.5), Isoleucine (30.6)
Leucine (52.2), Lysine (57.6), Methoinone (18.3),
Phenylalamone (27.3), Threonine (31.6) and Valine
(29.0).
Carbohydrate requirement
The carbohydrate-based feed stuffs are usually the
cheapest source of energy for cultured fish due to their
relative abundance. Buhler and Halver, (1961) reported
that relatively high levels of carbohydrates are tolerable
by carnivores’ fish and that dietary carbohydrate levels of
around 20% may be optimal. Fiber has no nutritional
value in feed (Sado, 1989) apart from aiding the passage
of food into the gut of fish. A dietary excess or deficiency
of useful energy can reduce growth rate because energy
needs for maintenance and voluntary activity must be
satisfied before energy is available for growth. Energy is
a nutritional requirement for the culture of animals.
Failure to include adequate quantity in diet may result in
reduced growth while excessive quantities of energy
results in undesirable fat deposition or reduced feed
consumption (NRC, 1993).
Fats requirements
Lipids include free fatty acids, triglycerides,
phospholipids, oils, waxes and sterol. All these lipids
provide dietary energy which is about twice as much as
the energy produced by carbohydrates and protein Sado
(1989) and Catacutan (1999) revealed that
homoeothermic animals have dietary lipids are an
important source of energy and the only source of
essential fatty acids (EFA) in fish, only differs in species
and from age and size (Shepherd and Bromage, 1992)
determining requirements for fatty acid is difficult for fish
because the metabolic requirement is very small and fatty
acids stored in the body or even carried over from egg
yolk can influence performance of the experimental fish
according to Lovell, (1987).
Vitamins and minerals
Vitamins are organic compounds required by fish in very
small amounts for growth, metabolism of tissue nutrients
and diseases resistant. Vitamin are either fat or water
soluble; water soluble are easy leached from polluted
feeds when they come in contact with water and they
Ojonugwa and Solomon 87
include thiamine, riboflavin, pyridoxine, Pantothenic acid,
Nicotinic acid, Biotin Inisitol, Choline, Folic acid, B-12 and
Ascorbic acid (Ayinla, 1991). In highly stocked plastic
containers, it is important to feed with complete diets
since it is doubtful if the nutrient supply of natural food
organisms in water body will be adequate to meet the
vitamin requirements of the fish. Mineral requirements of
fish is similar to those of terrestrial animals. fish requires
minerals in trace amount for tissue formation and other
metabolic activities.most important minerals are calcium
(Ca) and phosphorus (P) which must be supplied in
sufficient quantities (Lall, 1991) although fish absorbs
some of these minerals in water and reduce their
requirement, nevertheless, it is safer to supply adequate
amount of calcium in feeds to forestall possible deficiency
symptom in fish. Comparably, P is lower than Ca in
natural water so it does not occur in reasonable amounts.
The most reliable source of phosphorous (P) for fish is
through its diet Sado, (1989) reported that blood meal,
bone meal and limestone inclusion into feeds can
effectively take care of the deficiency.
Water quality parameters
Fish and other aquatic organisms such as shrimps and
crayfish are known to be very rich in protein and need to
cultivate these in clean water in the locality is highly
needed. The need for clean water to raise this protein
rich and needed aquatic commodity cannot be over
emphasized. The productivity of a given body of water is
determined by its physical, chemical and biological
properties. These environmental properties of water need
to be conducive for fish to grow well; therefore, an ideal
water conditions is a necessity for the growth and survival
of fish. The population density of organism of any water
system such as in land fresh water and lakes always vary
according to the physico-chemical factors such as
hydrogen-ion concentration (PH), dissolved oxygen (DO)
conductivity, nutrient and temperature (Abolude, 2007).
Temperature
Water temperature is one of the major environmental
factors that affects and controls food utilization at all
levels and stages of fish growth. The suggested
temperature ranges from 20 to 30°C while the lethal
levels are from 2 to 42°C. Fish are poikilothermic and
water plays an important role in their feeding as it affects
their metabolic activities, feeding potential, growth,
survival, reproduction in all species of fishes (Dupree and
Hunner, 1994). Temperature has a pronounced effect on
the rate of chemical and biological processes in water; for
instance, fish require twice as much oxygen at 30°C than
20°C (Adeniji and Ovie, 1990). It is recommended that
88 J. Anim. Sci. Vet. Med.
fish in the tropics be kept in water whose temperature
range is between 25 - 30°C (Auta, 1993). Sudden
increase in temperature will stress or even kill fish and
this has formed the basis for the acclimatization of fish
(Adeniji and Ovie, 1990). Temperature has been found to
affect the dominance and distribution of phytoplankton in
water as it influences the growth rates and mortality of
planktons and other organism (Orchutt and Porter, 1983).
Temperature is known to influence organisms to varying
degrees, depending on their sensitive thus fish survival in
plastic container depends on temperature and dissolved
oxygen (Countotant, 1987).
Dissolved oxygen
Dissolved oxygen in water is very essential to life in the
aquatic environments as it affects the physiology and
distribution of the aquatic organism. Nearly all aquatic
organisms with the exception of some bacteria must have
oxygen to survive and most of these organism mushes
extract their oxygen from liquid water. The two main
sources of oxygen into the aquatic environment are the
atmosphere and photosynthetic activities of aquatic
planks. The ideal range of dissolved oxygen in the water
must be at least 5mg/l is required to sustain fish and
other aquatic life in water bodies (Adakole, 2000).
Insufficient dissolved oxygen (D.O) in a water system
tend to cause anaerobic decomposition of organic
materials in water thereby leading to the production of
obnoxious (annoying) gases such as carbon dioxide,
hydrogen sulphides and methane which bubble to the
surface. The physiology of aquatic organism is such that
they can tolerate only narrow ranges of temperatures,
outside which they cannot function normally (Willoughby,
1976). Kutty, (1968) and Kutty and Sunders, (1973)
reported that Atlantic salmon stopped swimming when
dissolved oxygen concentration remained below 5ppm
but goldfish, tilapia and carps swims at oxygen level of 1
to 2 ppm. Inadequate dissolved oxygen has many effects
of fish like reduced feeding; impaired growth and leading
to fish becoming stressed thereby becoming susceptible
to diseases. Cold water fish require large amounts of
dissolved oxygen with temperature range of 5 to 15°C
while warm water fish with a temperature range of 20 to
40°C are able to survive with low oxygen content.
Hydrogen-ion concentration
The hydrogen ion concentration (pH) of any water is the
measurement of acidity or alkalinity of that water body. It
is usually measured on a scale of 0-14 with 7 being
neutral. The effect of pH on the chemical, biological and
physical properties of a water system makes its study
very crucial to the lives of the organisms in the medium.
Fresh waters with a pH ranging from 6.5 to 9.0 have been
known to be productive and recommended as suitable for
fish culture (Adeniji 1986; Auta, 1993). Increase in acidity
and alkanity of any water body may increase or decrease
the toxicity of poison in the water; solar radiation and
temperature accelerates photosynthesis, which in turn
increase carbon dioxide absorption altering the
bicarbonate equilibrium and producing OH- thus raising
the pH (Branco and Senna, 1996).
Hynes, (1974) observed that PH values below 5 or
above 9 are harmful to most animals within the normal
range, according to Wuhramann and worker (1982) and
Krenkel (1974) pH has more influence on some poison.
Chronic pH levels may reduce fish reproduction and are
associated with fish die-offs (Stone and Thomforde,
2006) (Adeniji and Ovie, 1990) reported that acid and
alkaline death point is approximately at pH 4 and 11
respectively.
In view of the above, the aim of the research is to
determine the effect of overstocking on the growth rate of
Clarias gariepinus
MATERIALS AND METHODS
Experimental fish
One hundred and forty fingerlings of clarias gariepinus
were obtained from a reputable farm: Efugo’s Farm in
Kuje Abuja, Nigeria. The fish were transported to the
Department of Biological Sciences University of Abuja in
50 litres plastic which was half filled with fresh water at
the early hour in the morning to avoid mortality due to
high temperature, and were acclimatized for one week
.The mean initial weight for the fish was 8.9±0.4 g and
the length was 0 to 10 cm. During the period of
acclimatization the fish were feed with coppens at 20%
body weight (10% in the morning 8:00 to 9:00 am and
10% in the evening 5:00 to 6:00 pm.
Feeding and measurement
At the end of the acclimatization period the fish were
randomly selected and stocked into four (4) circular
plastic bowls at different stocking densities of 10, 20, 30
and 40 for treatment 1, 2, 3 and 4 respectively. The bowl
with the lowest stocking densities (10) served as the
control. The positioning of the bowls allowed a natural
photoperiod of 12 h sunlight and 12 h darkness
throughout the experiment and the other forty are stocked
for replicates. The fish were feed with coppens (an
artificial pellated floating feed containing 42% crude
protein) with 10% body weight (5% in the morning and
5% in the evening between the hours of 8:00 to 9:0am
Ojonugwa and Solomon 89
Plate 1: Images showing how fishes are been stocked in different circular plastic bowls.
and 5:00 to 6:00pm respectively. The feed for each
treatment and its replicate were weighed in separate
nylon for onward feeding. The feed particle size
increased periodically as the fish grow. The fish were
weighed using a weighing scale at the commencement of
the experiment and on a weekly basis during the
experiment and a calibrated measuring ruler (cm) was
used to take the length of the fish at the commencement
of the experiment and weekly basis for 12 weeks.
Circular bowls and water management
The circular bowls of the same size with 80 litres capacity
per each were bought from Gwagwalada market. The
bowls were washed and filled with tap water to 40 liters
capacity (the fish were given equal room). The bowls
were covered with mosquito nets to prevent the
fingerlings jumping out and also intrusion of insect and
other foreign bodies (birds). The water in the bowls was
changed after three days interval to avoid accumulation
of toxic waste which will be harmful to the fish (Plate 1).
Growth response
To determine the growth response of the fish the follo-
wing parameters were calculated:
Mean weight gain (g)
MWG=Wt2-Wt1
Where, Wt1 = initial mean weight of the fish at time T1 and
Wt2 = final mean weight of fish at time T2
Specific growth rate (SGR)
SGR=100 (LogeWf - logeWi)/time (days)
Wf =final average weight at the end of the experiment, Wi
= initial average weigh at the beginning of the
experiment, Loge = natural logarithm reading and Time =
number of days for the experiment.
Survival rate (%)
Survival rate (%) = number of fish that survived X 100/
total number of the stocked
Feed conversion ratio (g)
FCR=weight of feed given/fish weight gain.
90 J. Anim. Sci. Vet. Med.
Mean length gain (cm)
MLG=Lt2-Lt1
Physiochemical parameter
Temperature
Surface water temperature was read twice daily to the
nearest °C with the aid of mercury in glass thermometer
and data observed were recorded.
pH
The pH of the water body was also carried out twice daily
with the use of water test quality apparatus containing
micro-pipette, a test-tube and an indicator. Water was
taken from the fish pond (treatments) with the use of
micro-pipette, and then released into a calibrated test-
tube, at the level of 10 ml, and then four drops of
indicator was added, to observe the acidity and alkalinity
of the water.
Dissolve oxygen
The alkaline Azide modification of winkers method was
adopted for determination of DO in water. 100 ml of the
fish water sample was transferred into a 250 ml conical
flask and 2 ml of manganese sulphate solution was
added, followed by 2 ml of sodium iodide azide reagent,
with a dropping pipette below the surface of the water.
The conical flask was stopped to exclude air bubbles and
the solution mixed thoroughly by inverting several times,
until a clear solution is obtained. More also, 2 ml of
concentrated sulphuric acid was added by allowing the
acid run down the neck of the flask and the flask re-
stopped and the solution mixed by gentle inversion until
dissolution is complete. The solution was titrated with
0.0125 m sodium thiosulphate (Na2S2O3.5H2O) solution
to a pale straw colour. 1 ml of starch solution was added
and the titration was continued by adding the thiosulphate
solution drop-wise until the disappearance of the blue
colour.
Calculation:
Mg
LDo =16000 x M X V
V2/V1(V1 − 2)
Where; M = molarity of thiosulphate solution, V = volume
of the thiosulphate used for titration, V1 = volume of the
bottle (250ml) with stopped in place and V2 = volume of
aliquot taken for titration.
Data analysis
Data were analyzed by analysis of variance (ANOVA)
(Snedecor and Cochran, 1982) and the differences
between means were examined using least significant
difference test.
RESULTS
Mean weight gain
The initial weight in all the treatment was 8.9±0.4 (9):
range was between 8.5 to 9.15 g while the mean final
weight in all the treatment was 109.9±35.9 g the range
was from 68.6 to 153.1 g. The daily weight gain shows an
inverse relationship; as stocking density increase, the
control pond (10) had the highest final mean weight of
153.1 g followed pond A (20) with 121.5 g and B (30) with
96.6 g while the least was recorded in pond C (40) having
mean final weight of 68.6 g. This result shows that there
was significant difference (P<0.05) between the mean
final weight gain in all the treatments which shows that as
the stocking density increases the weight gain decreases.
Feed conversion ratio
The analysis of the feed conversion ratio, which
expresses the efficiency of fish in converting food to flesh
was best in the control pond (10) having FCR of 4.76
followed by pond A with 5.14, pond B 5.45, and the least
was in pond C with 5.91. There was a significant
difference (P< 0.05) in the FCR in all the treatments.
Specific growth rate
The specific growth rate in this study shows that as the
stocking density increases growth rate decreases (Figure
1). The control pond had the best SGR of 3.05, pond A 2.
80, pond B 2.62 and the least was in pond C having 2.26.
One can also conclude that there was no significant
difference (P<0.05) in the SGR between ponds A, B and
C.
Survival rate
The mean survival rate ranged between 92.5 to 99.86%.
Control pond, pond A and pond B had the highest
survival rate while the least was in pond C.
Physiochemical parameters
The water temperature in all treatments (ponds) ranged
between 26.51±1.54 to 27.4±1.39°C. The temperature of
Ojonugwa and Solomon 91
Figure 1. Mean weight fish stocked at different stocking densities.
Table 1. Physiochemical parameters of water in all the ponds.
Parameters
Control
Pond A
Pond C
Temperature
26.51±1.54
26.33±1.61
27.4±1.39
pH
6.92±0.36
7.05±0.39
7.00±0.40
Dissolved Oxygen
5.41±2.18
4.79±1.85
2.65±1.97
the water in pond B and C was highest due to over
stocking (Table 1).
Hydrogen ion concentration
The hydrogen ion concentration ranged from 6.92±0.36
to 7.25±0.22 and the pH 7.25 was highest in pond B.
Dissolved oxygen
The dissolved oxygen (DO) during the culture period was
highest in the control pond 5.41±2.18 (Table 1).
DISCUSSIONS
The survival of clarias gariepinus ranged between 92.5 to
99.8% which is compared to a similar work done by
Otubusin, (2000) and Osofero et al. (2007) with a range
of 98.5 to 99.5%. The high survival rate recorded in all
the treatments could be attributed partially to the
physiochemical parameters and the good health
condition of the fish. This result also indicates an inverse
relationship between survival rate and stocking density. It
was observed that as stocking density increases survival
decreases (Figure 1). This is due to stress experienced
as a result of aggressive feeding behavior where energy
meant for growth is used up in frenzy feeding activities.
The growth and mortality of Clarias gariepinus cultured
at various stocking density were not initially affected by
density but the overall harvest in terms of final weight and
size were directly related to stocking density (Table 2 and
Figure 2). As the stocking density increases the weight
gain decreases. This depicts an inverse relationship as
was observed in similar works by Otubusin (2000).
Growth is a manifestation of the net outcome of energy
gains or losses within an environment. Weight gain is one
of the important indices for measuring growth which was
obvious among different ponds (treatments).
The water temperature range in this study falls within
the idea temperature required for catfish culture in fresh
water. The temperature range of 26.2 to 27.8 also agrees
with work of Adeogun et al. (2004) on the culture of
Clarias gariepinus in pond water.
The water pH range of 6.9 to 7.25 in this study falls
within tolerable range of which catfish cultivation which
agrred with the pH ranges observed by Thomas and
Michael (1999) and Khattab et al. (2000).
The dissolved oxygen of 5.4 recorded in this study also
agrees with similar work reported by Otubusin and
Olaitan (2001).
The feed conversion ratio in this study showed that the
FIGURE 1: Showing the mean weight fish stocked at different stocking densities.
92 J. Anim. Sci. Vet. Med.
Table 2. Growth performance of Clarias gariepinus in a circular plastic bowl at different stocking densities.
Pond
(SD)
IWT(g)
FWT(g)
MWG
SGR
FCR
SUR%
MLG
DWG
DLG
ILT
FLT
Control
10
8.5
153.1
144.6
3.05
4.76
99.86
16.62
1.56
0.18
8.71
25.33
A
20
8.66
121.13
112.98
2.80
5.14
99.65
14.43
1.21
0.15
8.76
23.19
B
30
9.2
96.6
87.4
2.62
5.45
96.66
13.16
0.95
0.14
8.85
22.01
C
40
9.15
68.6
59.45
2.66
5.91
92.5
12.99
0.65
0.14
8.03
21.02
SD, stocking density, SGR, specific growth rate, IWT, initial weight, FCR, feed conversion ratio, FWT, final weight, SUR,
survival rate, MWG, mean weight gain, MLG, mean length gain, DWG, daily weight gain, DLG, daily length gain, ILT, initial
length, FLT, final length.
Figure 2. Mean length fish stocked at different stocking densities.
control pond had the best conversion ratio of 4.76 while
pond C had the lowest of 5.91. The ability of Clarias
gariepinus to utilize feed nutrient at maximum
biochemical efficiency allows for higher feed conversion
ratio. This study shows that at higher stocking density
(over stocking) fish expend more energy due to
aggressive feeding than converting it to flesh. The overall
weight gain at stocking density of 40 fishes in a circular
plastic bowl was low and may be attributed to high
energy being expended during feeding (aggressive
feeding) whereas at lower stocking density of 10 fish
higher conversion to flesh and weight was obvious. The
value of feed conversion in this research shows that
stocking density has an effect on the ability of fish to
convert it feed into flesh and may also be attributed to
feeding techniques, quality of feed and temperature
variation.
Specific growth rate decrease with increase in stocking
density. The growth rate of 3.05 g observed in this study
was lower than 4.2 g reported for Clarias gariepinus by
Otubusin (2000).
Growth according to Bowen (1982) was determined
through the combined effects of quantity and food quality.
The quality and quantity of a given food or feed is directly
proportional to its ability to support growth.
Conclusion and recommendation
Over stocking is one of the major problems that affect the
growth rate of fish. Increase in stocking density result in
an increasing stress, which leads to higher energy
requirement and also causes a reduction in growth rate
and food utilization. Consequently, identifying the
optimum stocking density for specie is a critical factor not
only for designing an efficient culture system but also for
optimum husbandry practices. Controlling the fish size
and production are two important tasks to meet the
market demands. However, the stocking density of 10 to
20 fishes in a circular plastic bowl of 80 litres with a water
0
5
10
15
20
25
30
0 2 4 6 8 10 12 14
MEAN LENGTH OF FISHES
WEEK(S)
CONTROL (10)
POND A (20)
POND B (30)
POND C (40)
volume of 40 litre performed better than 30 to 40
fingerlings. That is, over stocking has a significant effect
on the growth rate of Clarias gariepinus. Therefore, it is
recommended that for optimum productivity, density of
fish stocked in a circular plastic bowl of 80 litres should
not exceed 25 fish. However, further research can be
carried out using different species of fish and different
container to determine the effect of over stocking on the
growth rate of Clarias gariepinus.
REFERENCES
Abolude, D. S (2007). Ethical issues in aquaculture production.
Journal of agricultural and environmental ethics no (4), 345-
370.
Adakole, J. A. (2000). The effects of diuretic agriculture and
industrial effluents on the water quality and biota of stream:
review in fish biology and fisheries no 21(1), 83-96.
Adeniji, H. A. (1986). Some limnological precautions for fish
farmers. Kainji lake Research Institute Annual Report, Pp. 54-
56.
Adeniji, H. A., & Ovie, S. I (1990). A simple guide to water
quality managements in fish ponds. Technical report series
NO.23, National Institute for Fresh Water Fishes Research
(NIFFR), New Bussa, Pp. 1-10.
Adeogun, O. A, fatioye, O. O. olayeye B. A., & Nigabili (2004).
The Relationship between some physicochemical parameters
an d planktons composition of fish productionin ponds in:
Aroaoye A. A (Ed). 2004 FISON conference proceedings
FISON lagos Nigiria.
Adikwu, I. A. (1999). aquaculture in Nigeria problems and
prospects. Journal of fishery technology. 1(1), 16-27.
Aksungur, N., Aksungur, M., Akbulut, B., & Kutlu I. (2007).
Stocking density on growth performance survival and food
conversion ratio or turbot (psetta maxima)in the net cages on
the southeastern coastof the black sea . Turkish Journal of
Fisheries and Aquatic Sciences, 7,147-152.
Auta J. (1993). Water quality management in fish pond
proceeding of National workshop on fisheries extension
delivery P.2.
Ayinla, O. A. (1988). The food and feeding habits of African
mud catfish Clarie gariepinus (burchell 1822) caught form the
wild Niomr. Technical Paper.
Ayinla, O. A. (1991) Fish feed and nutrition, paper presented at
the Fisheries society of Nigeria symposium 31st October 1991
at giginya hotel sokoto, p. 12.
Bakare, E. (1968). Food and feeding habits of non chillid fishes
of the Middle niger with a particular referee to Kainji Research
Basin.
Baras, E., langadere J. P. (1995). Fish telemetry in aquaculture
review and Perspectives. Aquaculture International, 3,,77-102
Barton, B. A., & Iwama, G. K. (1991). physiological changes in
fish from stress in Aquaculture with emphasis on the
response and effects of corticesteriods. Annual Review Fish
Disease, 10, 3-26.
Bjoernsson, B. (1994). Effects of density on growth rate of
halibut hippoglossus hippoglossus L. reared in large circular
tanks for three years. Aquaculture,123, 259-270.
Bolorunduro, P. I. (2006). The roles of research institute in
improving the Productivity of fish farming in Nigeria. In
Ojonugwa and Solomon 93
proceeding of the National workshop on improving the
productivity of fish Farming in Nigeria, Pp. 1-15.
Boujard, T., labbe, L., & Auperim, B. (2002). Behavior energy
expenditure and growth of rainbow in relation to stocking
density and food accessibility. Aquaculture Research, 33,
1233-1242.
Bowen, S. H. (1982). Feeding, Digestin and Growth Qualitative
Consideration, in: the biology and culture of tilapias d R.S.V.
pullin and R. H. lowe-McConnell ICLARM Conference
proceedings 7 ICLARM, Manila, Philistine. Pp. 141-156.
Branco, C. W. C., & Senna, P. A. C. (1996). Relations among
heterophic Bacteria chlorophyta total phytoplankton, total zoo
plankton and physical and chemical features in the paranoa
reservoir basicilia razic. Hydrobiologia, 337, 171-181.
Brummet, R. E. (2000) Indigenous species for aquaculture
development In Africa. Beeever Press , Nigeria, Pp. 5-8.
Buhler, D. R., & halver J. E. (1961). Nutrition of salmonoid
fishes ix Carbohydrate requirement salmon. Journal of
nutrition, 74, 307-318.
Catacutan, M. R. (1999).Growth and fatty acid composition of
penaeus monodon juvenile feed various lipids. Israel Journal
of Aquaculture 43(2), 47-56.
Coulibaly, A., Ouattara, I. N., Koné, T., N'Douba, V., Snoeks, J.,
Bi, G. G., & Kouamélan, E. P. (2007). First results of floating
cage culture of the African catfish Heterobranchus longifilis
Valenciennes, 1840: Effect of stocking density on survival
and growth rates. Aquaculture, 263(1), 61-67.
Countotant, C. C. (1987). Thermal preference: when does an
asset become a liability? Environmental Biology of Fishes,
18(3), 161-172.
De gram, G. J., Galemoni, F. & Banzoussi, B. (1996).
Recruitment control of nile tilapia , oreocromis niloticus, by
the African catfish , clarias gariepinus (burchell 1822) and the
African snakehead, ophio cephalus obscuris . I. A biology
analysis (aquaculture, 1976 (in press).
Degani, G., Ben-Zvi, Y., & Levanon, D. (1989). The effect of
different protein levels and temperatures on feed utilization,
growth and body composition of Clarias gariepinus (Burchell
1822). Aquaculture, 76(3-4), 293-301.
Dupree, K. H., & Hunner, J. V. (1994). The status of warm-
water fish farming and progress in fish farming research U.S.
Fish and Wild life service, Washington, D.C.,U.S.A.
El-Sayed, A. F. M. (2002). Effect of stocking density and
feeding levels on growth and feed efficiency of Nile tilapia
Oreochromis niloticus. Aquaculture Research, 33, 621-626.
Engle, C. R. & Valderrama, D. (2001). Effect of stocking density
on production characteristics, coasts, and risk of producing
fingerlings channel catfish. North American Journal of
Aquaculture 63: 201-207.
Eroudu, E. S., Nnubai, C. And Nwaduke, F. O. (1993).
Haematological studies on four catfish species raised in water
pounds. Journal of Applied Ichthyology, 9, 250-256.
Ewa-Oboho, I., & Enyenihi, U. K. (1999). Aquaculture
implications of growth and variation in the African catfish:
Heterobranchus longifilis (Val.) reared under controlled
conditions. Journal of Applied Ichthyology, 15, 111-115.
Fagbenro, O. A., Adeparusi, E. O., & Fapohunda, O. O. (2000).
Feedstuff and Dietary Substitution for Farmed fish in Nigeria.
National Workshop on Fish Feed Development and Feeding
Practices in aquaculture. FAO - NSPFS NIFFR
Fagbenro, O. A., Adeparusi, E. O., & Fapounda, O. O. (2003).
Feedstuffs and dietary substitution for the farmed fish in
94 J. Anim. Sci. Vet. Med.
Nigeria. In; National Workshop on Fish Feed Development
And feeding practices in Aquaculture organized by FISON in
collaboration with NFFR and FAO Special programme on
Food Security (SPFS). A. A. Eyo (Ed), New Bussa, 15th19th
September, Pp. 60-72.
Fagbenro, O. A., Balogun, A. M., & Anyanwu, C. N. (1992).
Optimal Dietary Protein levels for Heterobranchus bidorsalis
fingerlings fed compounded diets. Israel Journal of
Aquaculture, 2: 10-15.
FAO (1999). Fisheries statistics of Nigeria. Second edition.
Federal Department of Fisheries. Abuja.
FDF (2007). Fishery Statistics of Nigeria. Federal Department of
Fisheries Publication. Abuja, FCT, Nigeria. Pp. 11-24.
FOS (1997). Federal Office of Statistic: Facts and Figures about
Nigeria. 1996 Processed data, Lagos. Pp. 15-17.
Halver, J. E. (1978). Proteins and Amino Acids. Aquaculture
Development and Co-ordination Programme.
ADCP/REP/80/11, Pp. 32-40.
Haylor, G. S. (1991). Controlled Hatchery production of Clarias
gariepinus (Burchell, 1822): Growth and Survival of Larval at
High Stocking Density. Aquaculture and Fisheries
Management, 23, 303-314.
Haylor, G. S. (1992).Controlled Hatchery production of Clarias
gariepinus (Burchell, 1822). Growth and Survival of larvae
and fry at high stocking density. Aquaculture and Fisheries
Management, 23, 303-314.
Holm, J. C., Refstie, T., & Bo, S. (1990). The effect of fish
density and feeding regimes on individual growth rate and
mortain rainbow trout (Oncorhynchus ykiss). Aquaculture, 89,
3-4.
Huang, W. B., & Chiu, T. S. (1997). Effects of stocking densities
on survival, growth, size variation and production of tilapia fry.
Aquaculture Research, 28,165-173.
Huissman, E. A., & Ritcher, C. J. J. (1987). Reproduction,
growth, heat control and aquaculture potentials of the African
catfish (clarias gareipinus burchell, 1822). Aquaculture, 63,1-
14.
Hynes, H. B. N., & Pentelow, F. T. K. (1978). The biology of
polluted waters. Liverpool University, p. 202.
Irwin, S., O'halloran, J., & FitzGerald, R. D. (1999). Stocking
density, growth and growth variation in juvenile turbot,
Scophthalmus maximus (Rafinesque). Aquaculture, 178(1),
77-88.
Kerdchwen, N. (1992). L’alimentation artificielle d’un silure
Africain Heterobranchus longifilis (Teleostei: Clariidae):
Incidence du mode d’alimentation et. Première estimation des
besoins nutritionnels. Thèse de Doctorat, Université Paris 6,
France, 182p.
Krenkel, P. A. (1974). Sources and classification of water
pollutants. In Industrial pollution. Sax, I. N. (Ed.). Published
by Litton educational publishing, Inc. 7 New York. Pp. 197-
219.
Kutty, M. N. (1968). Respiratory quotients in goldfish and
rainbow trout. Journal of the Fisheries Board of Canada,
25(8), 1689-1728.
Kutty, M. N., & Sunders, R. L. (1973). Swimming performance
of young Atlantic salmon sakir as affected by reduced
ambient oxygen concentration. Journal of Fisheries Society
Research, Pp. 223-227.
Lall, S. P. (1991). Concepts in the formulation and preparation
of a complete fish diet, p1 12 W. S. S. De Silva (ed.) Fish
nutrition research in Asia. Proceedings of the forth Asian
Nutrition Workshop. Asian Fish Soc. Publ. Asian Fisheries
Society. Manila, Philippines, 5, 205.
Leatherland, J. F., & Cho, C. Y. (1985). Effect of rearing density
on thyroid and interrenal gland activity and plasma and
hepatic metabolite levels in rainbow trout, Salmo gairdneri
Richardson. Journal of Fish Biology, 27, 5838.
Lovell, T. (1987). Nutrition and Feeding of Fish. An AVI
Book,published by Van Nostrand Reinhold, New York.
pp.260.
Lovell, T. (1989). Nutrition and Feeding of Fish. An AVI Book,
published by Van Nostrand Reinhold, New York. 318p.
Ma, A., Chen, C., Lei, J., Chen, S., Zhuang, Z., & Wang, Y.
(2006). Turbot Scophthalmus maximus: stocking density on
growth, pigmentation and feed conversion. (Abstract)
Chinese J. of Oceanology and Limnology, 24(3), 307-312.
Machiels, M. A. M., & Henken, A. M. (1986). A dynamic
simulation model for growth of the African catfish, Clarias
gariepinus (Burchell, 1822). In: Effect of feeding level on
growth and energy metabolism. Aquaculture, 56, 29-52.
NRC (National Research Institute) (1993). Nutrient
Requirements of Fish. Committee on Animal Nutrition.
National Academic Press, Washington D. C. 114p.
Nwandukwe, F. O. (1993). Including Oocytes Maturation,
Ovulation and Spawning in the African Catfish
Heterobranchus longifilis using frog pituitary extract.
Aquaculture Fish Management, 24, 625-630.
Okorie, P. U. (2003). Socioeconomic Appraisal of Cage Fish
culture in Oguta Lake,Nigeria. http://aquaticcommons.org/
863/1/FISON2003_110-118.pdf.
Olaosebikan, B. D., Raji, A. (1998). Field guide to Nigerian fresh-
water fishes. Federal College of Freshwater Fisheries
Technology, New Bussa. Pp. 52-53.
Orchutt, J. D., & Porter, K. G. (1983). Diel vertical migration by
zooplankton: constant and fluctuating temperature effects on
life history parameters of Daphnia. Limnol. Oceanogr, 28(4),
720-730.
Osofero, S. A., Otubusin, S. O., & Daramola, J. A. (2007). Effect
of stocking density on Tilapia (Oreochromis niloticus,
Linnaeus 1757). Growth and Survival in Bamboo- Net Cages
Trial. Journal of Fisheries International, 2(2), 182-185.
Otubusin, S. O. (2000). The effects of different feedstuff on
tilapia, Oreochromis niloticus fry in floating net- hapa,
Nigerian Journal of Science, 34(4): 377-379.
Otubusin, S. O., & Olaitan, O. O. (2001). The production of
catfish (clarias gariepinus) in floating bamboo net-cage
system in Nigeria. ASSET: An International Journal (Series
A)}, 1(1), 77-82.
Otubusin, S. O., & Opeloye (1985). Preliminary Studies on
Bamboo Floating Cage and Net enclosure Fish Culture in
Kanji Lake Basin. Proc of the 4th Annual Conference of the
Fisheries Society of Nigeria, African Regional Aquaculture
Center (ARAC), Aluu, Port-Harcourt, Nigeria. 26th -29th Nov.
1985. Pp. 113-128.
Paspt, M. H., Dick, T. A., Arnason, A. N., & Engel, C. E. (1992).
Effect of rearing density on the early growth and variation in
growth of juvenile Arctic charr,Salvelinus alpines (L.).
Aquaculture Fisheries Management, 23, 41-47.
Rahman, M. A., Mazid, M. A., Rahman, M. R., Khan, M. N.,
Hossain, M. A., & Hussain, M. G. (2005). Effect of stocking
density on survival and growth of critically endangered
mashseer, Tor putitora (Hamilton), in nursery ponds.
Aquaculture, 249: 275-284.
Reed, W., Burchard, J., Hopson, A. J., Jennes, J., & Jaro, I.
(1967). Fish and Fisheries of Northern Nigeria. Gaskiya
Corporation. Zaria, Nigeria. 15p.
Rowland, S. J., Mifsud, C., Nixon, M., & Boyd, P. (2006). Effects
of stocking density on the performance of the Australian
freshwater silver perch (Bidyanus bidyanus) in cages.
Aquaculture, 253(1), 301-308.
Sado, E. K. (1989). Feed and Feeding: Artificial fish feed
formulation and nutrition, In: Fish Cage Culture Technology,
NIFFR TRAINING SERIES No. 1. NIFFR, New Bussa
Nigeria, Pp. 46-71.
Schram, E., Van der Heul, J. W., Kamstra, A., & Verdegem, M.
C. J. (2006). Stocking density-dependent growth of Dover
sole (Solea solea). Aquaculture, 252(2), 339-347.
Shepherd, J., & Bromage, N. (1992). Statiscal methods .6th
edition,Iowa state university press, Ames, IA,USA, p.593.
Skelton, P. (1993). A complete Guide to the Freshwater Fishes
of Southern African. Halfway House: Southern Book
Publishers Ltd.
Snedecor, G. W., & Cochran, W.G. (1982). Statistical Methods.
6th Edition, Iowa State University Press, Ames, IA, USA, p.
593.
Stone, N. M., & Thomforde, H. K. (2006). Understanding your
Fish Pond. Water Analysis report. Co-operative
Aquaculture/Fisheries Extension Programme. University of
Arkansas. Pine Bluff. U. S. Department of Agriculture and
County Governments C-operating. FSA - 9090. Pdf.
Ojonugwa and Solomon 95
Teugels G. G (1986). Asystematic revision of the African
species of the genus clarias (pisces :claridae)annales musee
royal de L’afrique central, science zoolgiques, 247, 1-99).
Teugels, G. G. (1982). Preliminary results of a morphological
study of five African species of the subgenus Clarias
(Clarias)(Pisces; Clariidae). Journal of Natural History, 16(3),
439-464.
Thomas, P., & Michael, M. (1999). Tilapia; life history and
biology, SRAC publication, 283, 1-199.
Willoughby, L. G. (1976). Freshwater Biology. Hutchinson and
Co. of London, Art. Britain p. 410.
Wuhramann, K., & Woker, H. (1982). Experimental
untersuchungen uber die Ammoniakund Blausaure Vergiftung.
schweiz Z. hydrol., 11: 210-244.
... Furthermore, provision of proper fish nutrition promotes growth and also enhances the overall health status of fish stock (Craig et al., 2017). High stocking density and poor water quality are important factors that cause stress to fish and subsequently weaken their immune system (Ojonugwa and Solomon, 2017). In the present study, however, stocking density and parameters that are used to assess the quality of pond water, such as pH, temperature and dissolved oxygen were not investigated. ...
Article
Full-text available
Antimicrobial resistance is a global health challenge caused by the ability of microorganisms including bacteria, fungi, protozoans and viruses to survive the effects of drugs that hitherto were effective against them. This study sought to investigate the presence of antibiotic-resistant bacteria and their corresponding molecular determinants in fish farms of the Central and Western Regions of Ghana. Management practices and antibiotic use at the fish farms were obtained through the administration of a questionnaire. Coliform and Gram-positive bacterial loads of catfish (Clarias gariepinus), tilapia (Oreochromis niloticus) intestinal microbiota, and pond water samples recovered on MacConkey Agar and Mannitol Salt Agar were determined. Bacterial isolates were identified using various biochemical assays. Antibiotic resistance profiles and possible responsible genes of bacterial isolates were determined using the disc diffusion and Polymerase Chain Reaction (PCR) methods respectively. The study revealed that none of the fish farm managers admitted using antibiotics for prevention and treatment of diseases and no major disease outbreak had ever been recorded. Bacterial loads of pond water exceeded the acceptable level of ≤100 E. coli and
... With an increase in population growth comes a corresponding reduction in food security due to the increased demand for protein. A decline of capture from the wild only serves to heighten this problem (Ojonugwa & Solomon 2017). Aquaculture serves as a means of providing cheap but quality protein to feed the growing population and mitigate this decline. ...
Article
Full-text available
The present study investigates effects of stocking density of Bagrid catfish, Chrysichthys nigrodigitatus on the growth performance, feed utilization, proximate composition and water quality. Fish with average weight of 7.34±2.36g were stocked in triplicates at densities of 20 fish/m 3 (SD 20), 40 fish/m 3 (SD 40), 60 fish/m 3 (SD 60) and 80 fish/m 3 (SD 80). Fish were fed twice a day to apparent satiation for 8 weeks. The results showed that growth performance parameters such as final length, final weight, specific growth rate (SGR), percentage weight gain (%WG), weight gain (WG), and average daily weight gain (ADWG), were significantly different amongst treatments. The highest growth values were obtained in group SD 40 and the least values were obtained in group SD 80. Fish stocked at SD 40 recorded the best feed conversion ratio, protein efficiency ratio and feed efficiency. Condition factor increased with stocking density but only from density SD 20 to SD 60 and decreased at SD 80. Water quality parameters were not significantly different among treatment except for nitrate but were all within acceptable ranges for fish culture. There was significant difference in coefficient efficient variation of final weight. There was no significant difference in proximate composition among groups. For optimum growth and feed utilization, this study recommends 40 fish/m 3 as the best stocking density for Bagrid catfish.
Article
Full-text available
Purpose. Forming a thematic bibliographic list of publications on certain issues of African catfish (Clarias gariepinus) biology and cultivation in Ukraine and abroad, as well as concerning the effects of rearing conditions on physiological, biochemical and fish-breeding characteristics of clariids. Methods. The complete and selective methods were applied in the process of the systematic search. The bibliographic core have been formed with the publications in Ukrainian, Russian and English from the fund of scientific library of the Institute of Fisheries NAAS of Ukraine. Results. There was composed the thematic list of publications with a total quantity of 112 sources covering the time interval from 1978 to 2017, as well as an article from the "Aquaculture" journal, dated 2018, and including the fish-biological characteristics of African catfish as representative of Siluriformes order, Clariidae family. The literary sources are arranged in alphabetical order by author or title, and described according to DSTU 8302:2015 “ Information and documentation. Bibliographic reference. General principles and rules of composition”, with the amendments (code UKND 01.140.40), as well as in accordance with the requirements of APA style — international standard of references. Practical value. The list may be useful for scientists, practitioners, students, whose area of interests covers the questions of cultivation and study of the biological features of African catfish.
Article
There were significant inverse correlations between rearing density of rainbow trout, Salmo gairdneri Richardson, and final body weight, plasma L-thyroxine (T4), triiodo-L-tryronine (T3), cortisol and protein concentrations, plasma T4/T3 ratios and thyroid epithelial cell height. In addition, hepatosomatic indices and plasma free fatty acid concentrations were higher in fish reared at low (134 g l-1) density compared with groups reared at medium (210 g l-1) or high density (299 g l-1), and the post-feeding (3·5-4h) elevation in plasma glucose and triglyceride levels evident in trout maintained at low rearing density was not found in those fish reared at higher densities. There were no significant effects of rearing density on hematocrit, carcass composition, hepatic glycogen and lipid levels and interrenal nucleus size.
Chapter
Nutrients must be provided in appropriate amounts and in forms that are biologically usable for optimum performance by the animal. Therefore it is as important to know the bioavailability of the nutrient as the dietary requirement. A respectable amount of data is available on digestibility of gross energy and crude protein in commercial ingredients used in fish feeds. There is, however, much less information on bioavailability of vitamins, minerals and amino acids from various natural and synthetic sources. In many cases, assumed availability values for nutrients are used to formulate fish feeds which are probably far from accurate. Examination of data presently available supports this contention.