EXPERT TOPIC - Tilapia

July | August 2012
EXPERT TOPIC - Tilapia

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The International magazine for the aquaculture feed industry

EXPERT T●PIC

TILAPIA
EXPERT TOPIC

Welcome to Expert Topic, a new feature for International Aquafeed. Each issue will
take an in-depth look at a particular species and how it's feed is managed.

14 | InternAtIonAl AquAFeed | July-August 2012

EXPERT T●PIC

4 1

5

3
2

1
Effects of dietary ous alternatives spearheading environmental conversion ratio of fish fed KDF was
friendly and nutritive-sustainable aquaculture also significantly improved (P=0.012): this
potassium diformate approaches. time the improvement was 4.5 percent.
Dietary potassium diformate (KDF) has Data on mortality were inconclusive, since
on juvenile tilapia been tested in tilapia aquaculture since 2005 some of the trials were carried out under
and since then numerous publications and clean laboratory conditions, while others
– a performance analysis conference contributions on the use of KDF employed a challenge with potentially path-
in juvenile tilapia have been published from ogenic bacteria, such as Vibrio anguillarum,
Europe, America and Asia. This study analysed Streptococcus agalactiae, Streptococcus iniae
by Christian Lückstädt, Animal
the average impact of the additive from all and Aeromonas hydrophila. In these cases,
Nutritionist, ADDCON, Germany
published studies on its effect on performance dietary KDF, ranging from 0.2 percent till

G
parameters such as weight gain, feed efficiency 0.5 percent reduced mortality (P<0.05)
lobal production of farmed and mortality. when employed against V. anguillarum; it
tilapia in at least 85 countries The final data-set contained the results tended to reduce (dosages between 0.2-
exceeded 3 million t in 2009 of eight published studies, comprising 18 0.6%) mortality caused by S. agalactiae and
and requires high-quality fish trials with KDF-inclusion, which ranged from A. hydrophila, while it had no effect (KDF
feeds. In such intensive aquaculture produc- 0.2% to 0.75% and covered 3,040 fish. Data ranging from 0.25-0.75%) on mortality
tion, bacterial diseases have been identified were subjected to statistical analysis and a caused by S. iniae.
as a major cause of economic loss to pro- significance level of 0.05 was used in all tests. In general, results show significantly
ducers. Feeding antibiotic-medicated feeds Results are expressed as percentage differ- improved growth and FCR in tilapia fed
is a common practice to treat bacterial ence from the negatively controlled fish. with dietary potassium diformate, while
infections. Prophylactic use of antibiotics as its beneficial impact against pathogenic
growth promoters in aquaculture produc- table 1: effects of potassium diformate bacteria seem to be bacterial-challenge
tion has also occurred widely. in tilapia diets against negative control dependent. If calculated as fish productivity
performance (responses as per cent of
index, which is a function of weight gain,
negative control) – data-set consists of eight
However, growing awareness from con- published studies covering 3,040 fish survival and FCR (Lückstädt & Kühlmann,
sumers and producers of aquaculture species 2011), the improvement extended to
Dosage (%) Feed intake Weight gain FCr
has resulted in a demand for responsible and almost 17 percent (P=0.020). The use of
sustainable aquaculture. Regulatory authorities KDF in tilapia feeding is therefore sup-
0.41 +2.05 +5.59 -4.46
in most exporting countries now focus on ported as a promising alternative in the
P.level 0.162 0.009 0.012
the misuse of antibiotic growth promoters contemporary aqua-feed industry in order
(AGP) in aquaculture, while public attention The average level of dietary potassium to contribute to an ecologically sustainable
has shifted towards sustainable production diformate from the data-set in all treated tilapia production.
methods. fish was 0.41percent. Only a numerical This paper was presented at the XV
Thus, alternative additives to replace increase of feed intake (2.1%) could be International Symposium on Fish Nutrition
AGPs, which have been banned in EU animal monitored (P=0.16) compared to fish and Feeding Molde, Norway June 4-7, 2012.
feeds since 2006, have had to be tested. without the additive. However, the per- Originally published on www.engormix.com
Dietary organic acids, and especially potassium formance of tilapia, based on final weight
diformate – the most widely tested organic was significantly increased by 5.6 per- More InforMatIon:
acid salt in aquaculture, are among the vari- cent (P=0.009). Furthermore, the feed Website: http://www.addcon.com

July-August 2012 | InternAtIonAl AquAFeed | 15

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2
EXPERT T●PIC

Cage characteristics of capital investment and cash flow, and scale
Brazil holds about 10 million ha of freshwa- harvests for consistent sales and production
ter in dams, rivers, lakes and man-made res- flow.
ervoirs. Floating cages have become the most Tilapia farms that operate with cages
popular system for rearing tilapia in Brazil in beyond 300 m3 in volume are sometimes
areas with suitable water quality, flushing rates vertically integrated from fingerling produc-
and water depth. tion to fish distribution. They operate with
Tilapia cages are simple to build, inexpen- processing plants and sales contracts that
sive (US $400 for a 6-m3 cage) and easy to require the harvest of large volumes of tilapia
manage. Cages are usually constructed with at a time. In larger-volume cages, final stock-
rigid or flexible nets made from plastic-coated ing densities are reduced to 60 kg of fish/m3.
galvanized steel, stainless steel or synthetic They have the disadvantage of poor flexibility
fibers such as polypropylene. and maneuverability, but on the other hand,
Steel nets are more widespread, as they can represent significant savings in labor force.

Tilapia better resist predatory fish such as the pira-
nhas found in some inland areas in the
country. Cage frames are made from stain-
Nursery
Sex-reversed tilapia are usually sold to

cage farm less steel or galvanized steel. Strong, long-
life, high-density polyethylene frames are less
widely available and more costly, but have
grow out farms as fry with wet body weights
between 0.2 and 0.5 g. A thousand tilapia fry
cost US $30 to $45, depending on quality,

management become the choice of farms that operate with
medium-volume cages.
In sites close to shore, stationary cages
location and availability. When available at
short distances, some farmers prefer acquiring
juvenile fish of 10- to 30g weight, although

in Brazil are spaced two to four metres apart in
groups and docked with anchoring poles fixed
inshore. Otherwise, submerged chains and
their prices may exceed $80/1,000 fish. At
this stage, fish mortality can be significantly
reduced and the growout cycle shortened.
ropes attached to concrete bottom weights Earthen ponds may be used for the nurs-
by Alberto J. P. Nunes, from the Instituto
are used as mooring systems. To facilitate ery of Chitralada fry prior to stocking in
de Ciências do Mar – Labomar, tilpia cage
farm management specialist. Originally daily management, many farms now adopt cages. However, cages equipped internally
published in Global Aquaculture walkways made from wood attached to with flexible 5mm mesh nets are usually
Advocate empty barrels or plastic containers. more common, as
Most cages used for tilapia rearing have
small volumes of four to 20 m3. These

M
uch of Brazil’s expanding can be round or square in
tilapia aquaculture takes place shape with heights not
in floating cages with sturdy greater than two
frames and nets made from metres. The
plastic-coated steel or polypropylene. cages
can
Although larger cages are also used, most
cages have small volumes up to 20 m3 that
support high stocking densities and intermit-
tent harvesting without overstressing the
fish. Earthen ponds may be used for the
nursery of fry, but compartments in
cages are more common. Size grading
is a major management component.
Tilapia were first brought to
Brazil in 1953, but only over the
past decade has tilapia farming
grown to commercial scale. Since they facilitate fish han-
1999, the industry has expanded dling and transfer to grow
at an average annual growth rate out cages. In cages, it takes five
of 18 percent. In 2009, the Brazilian to eight weeks to grow 0.5g fry to 30g
Ministry of Fisheries and Aquaculture reported juveniles, depending on stocking density, feed
the tilapia harvest was 133,000 metric tonnes. safely operate with high stocking densities and water quality.
Over the years, Brazilian farmers have used (starting at 120 kg tilapia/m3) due to rapid
a number of tilapia strains, starting with the water exchange. Size Grading
Florida red and more recently the genetically Since much of Brazil’s tilapia sales are Tilapia growth can vary widely within the
male tilapia. Nile tilapia, Oreochromis niloticus, domestic and retail, small-volume cages allow same stock, especially when the fish are subject-
Chitralada strain, brought from Thailand in the harvest of fewer quantities of fish with- ed to high density. This is in part due to genetic
1995, has established itself as the main strain out imposing stress on the greater stocked differences, but also because of competitive
farmed in the country. Much of the tilapia population. As cages move beyond 10 m3 in interactions among fish. Some fish outcompete
aquaculture takes place in floating cages near volume with monthly harvests exceeding 10 others for feed and consequently grow faster. As
many of Brazil’s coastal areas. metric tonnes, farms require a moderate level


EXPERT T●PIC

a result, size grading becomes a major manage- are usually sorted manually by eye, but in large Cage operations equipped with walkways
ment component of tilapia cage farming. operations, this procedure can be mechanised. allow more detailed inspections of feed con-
When tilapia are transferred to different sumption. They facilitate feed handling and
cages, it also allows moving the stock to clean Feeds, feeding storage, and promote feed delivery to as often
units with larger mesh sizes, which promotes Cage-farmed tilapia in Brazil received as eight times a day during grow out com-
greater water exchange within the rearing unit. only extruded diets. Feed protein content, pared to three times when distributed from
From 5mm mesh sizes, 10g fish are usually pellet size and suggested feeding rates may feed boats. Walkways also allow the collection
moved to cages with mesh sizes of up to 15 vary according to the feed manufacturer. of fish debris and more frequent clean up of
mm. Then 30 to 200g tilapia are held within Fish feeds tend to be high in protein con- feeding rings or net curtains.
nets of 15 to 25mm mesh. The mesh on nets tent at initial stages and drop as fish attain
for fish larger than 200g is 25mm or wider. larger sizes (Table 1). Growout and finishing Perspectives
Grading frequency depends on a number feeds are usually 32 percent in protein con- Tilapia cage farming will continue to grow
of variables, including the targeted fish size tent and may represent up to 80 percent of quickly in the years to come in Brazil to
at harvest, number of cages available on site, all feeding costs at a cage farm. Feed costs reduce the increasing domestic deficit of
stock size variation, degree of prevalent stress to produce a one kilo tilapia can range US fisheries products in the country. Tilapia
and health status of the stocked population. $1.10-1.30/kg of fish harvested. As such, are mostly marketed fresh and degutted at
Many farmers target tilapia above 900g in feed management is critical to the econom- weights of 700 to 900g. Farm gate prices
weight to achieve premium prices. For this ics of a cage operation. range US $2.00-2.80/kg.
fish weight, grading can be carried out two to To determine maximum ration sizes, farm- Today a great proportion of Brazil’s tilapia
three times in a production cycle (Figure 1). ers usually follow suggested rates from com- production is consumed in the countryside,
During the rainy season, when fish become mercial feeding tables. However, rations are but the fish are also now found in large super-
more susceptible to disease outbreaks, there adjusted on a daily basis depending on fish market chains, restaurants and fish markets
is a reduction in tilapia stocking density as well appetite. In small-volume cages, rations are all over the country. As capture fisheries
as grading frequency. When size grading is never delivered in full amounts. Initially, fish continue to decline in Brazil and more city
adopted, final tilapia body weight variation can can be fed only half of the calculated ration. residents learn to appreciate tilapia, increasing
be reduced from 40 percent at initial stages to The remainder is offered if the first ration is demand will further drive new entrepreneurs
about 15 percent at harvest time. Tilapia are fully consumed within 30 minutes after dis- into tilapia aquaculture. In this new scenario,
often sorted into four size categories, with the tribution. After this period, uneaten feed can medium-size cages and more mechanised
smallest, most challenged fish removed as early be oversaturated with water, and the heavier practices will emerge to keep pace with large-
as possible since their delay in growth cannot pellets exit the confined feed area, leading to scale production and more-efficient opera-
be recovered during the production cycle. Fish feed loss. tions.

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EXPERT T●PIC

Tilapia genetic inconsistent, and wasteful. It was then found
that certain hybrids between different tilapia
species (O.niloticus and O.aureus) gave very high
pany) a few years ago and is now marketed
globally as Genomar Supreme tilapia (GST) and
the processed fish as TRAPIA (traceable tilapia)

strains and percent male progeny. The downside with this
technique was that it required hatcheries to
hold two separate stocks of tilapia species, and
ensuring full genetic traceability of their products
to the food industry. Trapia is produced in
Genomar’s cage farms in lakes in Malaysia and

hatchery as the purity of tilapia stocks deteriorated, the
technique became unviable.
Researchers then discovered that tilapia fry,
mainly exported to the USA.
Since the sale of the GIFT latest genetic lines
to Genomar, the Philippines have carried on

technology when fed male sex hormones for the first month
after hatching, were able to change sex, from
50- 50 male to female ratio, to ratios of almost
with their own Genetic Improvements of the
GIFT line and market the GIFT Excel line now.
These lines are all based on the original genetic
100 percent male fry. This is a highly variable stocks collected in Africa in the 1980s.
by Eric Roderick technique due to hormone purity and operator Another well-known stock is the Chitrilada
experience. strain which is farmed extensively in Thailand. It

T
One of the major challenges facing the originated as a gift to the King of Thailand by the
ilapia is a diverse group of over 100 industry is that use of Methyl Testosterone will Emperor of Japan in 1965, and was maintained
species, but surprisingly only a handful be phased out. This is overcome by the latest as a pure line in the Royal Jitralada Palace in
of species are cultured commercially technology to effectively provide all male fry - Bangkok for many years before being distributed
and only one species, the Nile tilapia, the YY Male Technology developed by Fishgen. throughout Thailand by the Thai Department
Oreochromis niloticus accounts for 95 percent of After many years of research in the UK and in of Fisheries in 1967. Since then it has been
global production. the Philippines, Fishgen produced supermale improved by selective breeding programmes
tilapia which had two Y chromosomes instead and is now widely farmed in South and Central
Culture systems range from small backyard of the usual Y and X chromosome. Females America, particularly Mexico and Brazil. This
operations producing a few fish to sustain a small have two X chromosomes. These supermales stock also originated from Egypt.
family, to huge agro-industrial units producing produce only male fry addressing the problems The only other tilapia genetic line com-
of a future ban on hormonal sex reversal. mercially used extensively around the world is
the YY Supermale strain, developed by Fishgen
Which strain in the UK. This stock is also based on the Nile
Deciding on which commercial strain of Tilapia from Egypt, but the main difference
tilapia to use in a new tilapia project can be between this line and all the others available, is
daunting, and there are many commercial stocks that no hormones are required to sex reverse

3
available globally. The farm’s location can have the fry for growout, as the YY supermale has
a deciding influence as there are restrictions been specifically bred to sire only male offspring.
on importation of some strains from some
countries, to minimise disease and biodiver- Hatchery systems
sity issues particularly in Africa where there are Tilapia hatchery systems are diverse with
many unique endemic strains of tilapia, requiring cost of construction and production of tilapia fry
protection from contamination by the careless varying enormously, from basic pond hatcheries
introduction of new genetic lines, where escap- in tropical countries costing almost nothing, to
ees could interbreed or outcompete with the expensive high-tech bio-secure indoor recircula-
pure endemic species. tion systems. The low-cost breeding systems
utilise simple earth broodstock ponds, with a
The big four shallow area around the edge where the fry once
There are currently four main genetically released from the female’s mouth, tend to con-
improved commercial lines that are globally gregate in tight shoals and are collected with large
over 20,000 metric tonnes annually. With the distributed and proven to be fast growing. The dip nets or small seine nets, on a daily basis. Larger
rapid growth of the global tilapia industry over biggest genetic improvement programme was hatcheries use lined ponds in poly-tunnels which
the past 25 years, genetic improvement pro- the GIFT project (Genetically Improved Farmed give better temperature control, biosecurity and
grammes enable a more profitable industry to Tilapia) and the current stock was originally predator protection. The fry are incubated by the
benefit from the increased popularity of tilapia produced from eight strains of the Nile Tilapia female which is less efficient than removing the
as a global food commodity. collected from Africa in the 1980s. fertilised eggs from the female’s mouth and using
From humble beginnings being farmed for After extensive selective breeding pro- artificial incubators to hatch the fry.
the Pharaohs in Ancient Egypt 4,000 years ago, grammes carried out in the Philippines between Many of the world’s largest tilapia hatcheries
the Aquatic chicken is now a very important 1988 and 1997 by ICLARM (Now WorldFish are in Asia, where 75 percent of global tilapia
globally traded commodity with production Center) in collaboration with AKVAFORSK (The production takes place. They utilise Hapa-based
worldwide of 3.23 million metric tonnes in 2011 Institute of Aquaculture Research in Norway) a production systems, where the broodstock are
and still growing. new strain was produced and distributed glo- bred in long hapas (net pens) and the eggs are
bally. World Fish Center has moved to Penang, harvested from the female’s mouth every five
Supermales Malaysia now and the breeding programme is days. This is done by opening the buccal cavity
Most commercial farms only grow male still carried on scientifically and commercially in of the female and gently rinsing the eggs out of
tilapia, which grow much larger and faster than both Malaysia and the Philippines. the mouth into a bucket.
females. This was initially achieved through The commercial rights to a recent GIFT
manual hand-sexing of the fingerlings, and dis- genetic line was sold to Genomar (a Norweigian Global perspective
carding the females, which was labour intensive, Venture Capital Genetic Improvement com- With global tilapia production still grow-


EXPERT T●PIC

ing steadily, hatcheries are also tilapia producers will be to find new markets
expanding to provide fry for the and to overcome stiff competition from
grow-out farms and some of the Pangasius species (Basa and Tra) import-
biggest hatcheries now have the ed from Vietnam. This is especially true in
capability to produce one million European markets which is still seen as a new
fry per day. high value market for tilapia producers around
At present the main tilapia pro- the world. Spain imports 20 percent of the
ducing countries are China, Egypt, EU total and Poland 33 percent but these are
Thailand, Indonesia, Philippines, mainly frozen tilapia from China with demand
Costa Rica, Ecuador, Mexico and fuelled by the low prices reflecting the current
Honduras. There are large hatcher- economic downturn throughout the EU.
ies in all these countries but the Rapidly expanding importers of tilapia
biggest farms are vertically integrated are Russia and the Middle East, but as
units which produce their own fry China becomes far wealthier, consuming
to minimise biosecurity issues and more of its own tilapia domestically, price
ensure supply of fry. increases and possible shortages of tilapia
Regal Springs is one of the world’s as an export commodity are possible.
largest tilapia businesses, producing Many countries are ramping up production
over 70,000 metric tonnes in 2010 in to fill this perceived new demand. These
several countries around the world. are Vietnam, Bangladesh, Brazil, Egypt and
ACI in Costa Rica is one of the larg- Malaysia, where government support is
est individual farms. Both companies helping to drive this new wave of expan-
export all their production as fresh sions. The main growth areas are in value
fillets to the USA. Biomar is just added products particularly in the produc-
completing its brand new high tech ing countries so increasing profitability, and
feedmill very close to the ACI farm filling new and growing markets. Tilapia’s
to meet the growing demand for future is rosy.
tilapia feed in Central America.
More InforMatIon:
Future markets
Eric Roderick, FishGen
With the tilapia market firmly Tel: +44 7973 135609
established and growing in the USA Email: sales@fishgen.com
and globally, future challenges for Website: www.fishgen.com

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EXPERT T●PIC

most herbivores such as tilapia are fed
feeds containing only 25 to 30 percent

4
protein. This gives the impression that
herbivores are more efficient convert-
ers of protein into growth.
However, expressing protein
requirement based solely on dietary
inclusion levels is incomplete if feed
intake is not considered. Protein intake
is the product of the protein content of
the feed and the total amount of feed
Figure 1: Energy requirements of
consumed. As such the protein demand tilapia for maintenance and growth
per kilo of fish produced will give a clearer (at 27°C)
picture of the overall efficiency of the species
in question.
Generally speaking, in order to formulate
feeds for fish two main issues have to be

Feed addressed: a) what are the requirements and
b) how can we cost-effectively meet those
requirements.

formulation First, tilapia - like all animals - need energy
and protein. This seems trivial, but the chal-
lenge is to determine how much energy and

and feeding protein has to be supplied to guarantee opti-
mal growth and most efficient feed utilisation.
Second, what are the sources of energy
Figure 2: Protein requirements of
tilapia for maintenance and growth
(at 27°C)

strategies and protein? Various potential feed ingredi-
ents have to be evaluated for their nutritional
value, chemical composition and their avail- Digestible energy needs (kJ) = a × body weight

for tilapia ability to the fish.

Calculating requirements
(kg)0.80 + c × energy gain (kJ)
Where c = cost of production in units of dietary
energy to deposit energy as growth.
Nutrient requirements are generally
by Ingrid Lupatsch, Centre for Sustainable
defined for animals of a given age and for a The same approach is used for the quan-
Aquaculture, Swansea University, UK
specific physiological function, such as mainte- tification of protein, except for the use of

T
nance, growth or reproduction. In fish farming a different exponent of b = 0.70 for body
ilapia are now the world’s second growth is one of the major goals. Growth weight as determined for several fish species
most popular group of farmed fish means deposition of new body components, (Lupatsch et al. 2003, Lupatsch and Kissil,
after carp. Worldwide production which in fish consist mainly of protein and lipid 2005).
exceeded 2.5 million tons in 2007 besides water.
according to FAO and demand continues at The feed has to supply the material for Digestible protein needs (g) = a × body weight
a steady pace. building new tissue, but also the energy need- (kg)0.70 + c × protein gain (g)
ed to deposit the new growth. In addition to Where c = cost of production in units of dietary
Tilapia are farmed worldwide in inland these, energy and protein for maintenance protein to deposit protein as growth.
aquaculture in various kinds of facilities and have to be supplied as well. Therefore, this
production strategies. The majority is still basic calculation dictates that the energy and Using this approach energy and pro-
grown extensively in polyculture but more protein requirement of a growing fish is the tein requirements are quantified as abso-
and more intensive monoculture systems are sum of its needs for maintenance plus growth. lute requirements per fish body mass and
being used where the manufactured feed is The energy and protein requirement for anticipated daily weight gain and only then
the only source of energy and protein. maintenance at a constant temperature is expressed as an inclusion level in the feed.
Tilapia are often called the ‘aquatic chick- primarily dependent on body size. It is pro- The necessary parameters to obtain are
en’. Their success is attributed to a tolerance portional to the metabolic body weight in the thus the following:
to wide ranges of temperature and salinity, form of the equation, a x BW (kg)b, where a is
resistance to disease, their ability to reproduce a constant, characteristic of a certain fish spe- Growth data and feed intake
in captivity, and their capacity to grow well cies at a set temperature and b is the expo- A prerequisite for estimating feed require-
at high stocking densities, which make them nent of the metabolic weight which in fish ments of tilapia is to define its maximal
feasible for farming under various culture has been determined as b = 0.80 (Lupatsch potential for growth. This modelling requires
systems. et al. 2003). growth data from trials, where feed supply in
Tilapia as herbivores are perceived to be The requirement for growth is dependent terms of energy and nutrients is not limiting
more sustainable and whilst feeding on a low on the amount and the composition of the and optimal growing conditions are met. It is
trophic level, are able to convert low cost weight gain including the metabolic costs to though necessary to define these parameters
feed into high quality protein. There is contin- deposit new growth. for different stocks or strains as different
ued criticism that carnivorous fish are thought Daily energy requirements per fish in selection programs result in faster growing
to require high levels of protein in their feeds units of digestible energy can therefore be strains of all male Oreochromis niloticus such as
(that are mostly supplied by fishmeal) while expressed as: for example the GIFT strain.


EXPERT T●PIC

table 1: Protein and energy requirements of tilapia grown at 27°C

Body weight, per fish 25g 150g 300g

Weight gain1, g / day 0.70 1.86 2.72
energy requirement

Demaint2, kJ /fish /day 2.90 12.17 21.18
Degrowth3, kJ/fish /
day 7.42 21.81 33.11
Dem+g4, kJ /fish /day 10.32 33.98 54.29
Protein requirement

take your
DPmaint5, g /fish /day
production to the
0.048 0.170 0.276
DPgrowth6, g/fish /day 0.238 0.634 0.926
DPm+g7, g /fish /day
DP/De ratio g/MJ8
0.286
27.7
0.803
23.6
1.202
22.1
TOP of the
1Predicted weight gain for tilapia at 27°C aquafOOd chain.
2DE required for maintenance: 55.5 x BW (kg) 0.80

3DE required for growth: (weight gain x body energy) x 1.61 (cost
of production) Many leading aquafeed manufacturers in the
4DE required for maintenance and growth industry count on Extru-Tech to engineer
5DP required for maintenance: 0.64g x BW (kg) 0.70 the perfect aquafeed production solution.
6DP required for growth: (weight gain x body protein) x 2.13 (cost
of production) Industry leading equipment and engineered
7DP required for maintenance and growth
production advantages will give you the
8Dietary DP/DE ratio for optimal protein utilisation
upper hand over the competition. Could
you use a cost effective improvement in
The following equations are all based on each gram weight performance and finished product quality?
trials carried out in Israel using male hybrid of gain is assumed to
O. niloticus x O. aureus at a water temperature equal the body com- Contact one of the aquafeed Consultants
of 27°C. position at a certain at extru-tech today at 785-284-2153.
The equation defining the relationship size.
between daily weight gain and fish size There is an
appears below: increase in energy
content with fish
Weight gain (g / fish / day) = 0.12 × Body size, whereas the
weight (g) 0.547 protein content
remains quite con-
Another prerequisite is an assessment stant at 160 mg/g
of the maximum voluntary feed intake, the fish
amount or bulk that the fish is physically able
to consume, this is needed to adjust the ener- Energy (kJ / g fish
gy density and nutrient density of a potential ) = 5.53 × BW (g)
feed. The following relationship between 0.055

voluntary feed intake and fish size was found: Protein (mg / g fish
= 160.2)
Feed intake (g / fish / day) = 0.15 × Body
weight (g) 0.600 The fact that pro-
tein content remains
quite stable and ener- Corporate offiCe
Composition of weight gain gy content is increas- P.O. Box 8 • 100 Airport Road
As a large proportion of the energy and ing with increasing fish Sabetha, KS 66534, USA
protein consumed by the fish is retained as size is typical for most Phone: 785-284-2153
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Fax: 785-284-3143
growth, the composition of the gain is a main fish (Lupatsch 2009). extru-techinc@extru-techinc.com
factor determining the subsequent energy and However, compared www.extru-techinc.com
protein requirement. When measuring whole to species such as
body composition of fish at increasing sizes, salmon or gilthead sea

ET-221A.indd 1 1/20/12 1:57 PM

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table 2: nutrient composition of selected ingredients used in bream, tilapia can be catego- Ingredient evaluation
practical feed formulations (per kg as fed) rised as a lean fish, a fact which and feed formulation
Crude Digestible Gross Digestible in the end will affect the dietary As mentioned before, once the requirements
protein, g protein, g energy, MJ energy, MJ protein to energy ratio. are known, various potential feed ingredients have
to be evaluated for their nutritional value, chemical
Fish meal 635 573 19.91 17.76 Maintenance composition and their availability to the fish. Table
Corn gluten meal 604 559 21.65 18.06 requirements 2 provides nutrient composition including digest-
Soybean meal 441 398 17.68 14.94 and efficiency ibility data of several ingredients that are commonly
To determine the main- used in aqua-feeds (Sklan et al. 2004).
rapeseed meal 366 311 19.49 11.17
tenance requirement as well Table 3 describes two potential feeds
Sunflower meal 378 336 17.87 11.70
as the relationship between that could be formulated from commercially
Wheat meal 118 94 17.69 12.72 weight gain and feed intake, available ingredients. The feeds describe a
Corn 79 59 17.52 10.76 groups of tilapia are fed 30 percent protein feed, commonly used
increasing levels of feeds with a in tilapia farming and a 40 percent protein
known digestible energy (DE) and digestible pro- feed.
table 3: Proposed feed formulations for two sets tein (DP) content. Feeding levels included a zero The full amount of protein consumed by
of commercial feeds – low protein and high protein
group (no feed) up to maximum voluntary intake tilapia is a function of the quantity of feed and
(for ease of presentation vitamins, minerals and other
supplements are considered under ‘others’). at a point when the fish refused to eat more. the protein content of that feed. As the daily
Figure 1 demonstrates that the relationship requirements for protein do not change, the feed
low High
Feed protein protein between daily DE consumed (x) and energy amount fed has to be higher when offering the
retained (y) is linear and can be described by low protein feed (Table 4), which will result in an
the following equation: increased FCR. In this case one has to consider
Ingredients (g kg-1) the cost of growing one kg of fish and not just the
Fish meal 100 200 y = - 34.4 + 0.62 x cost per 1 kg of feed.
Corn-gluten 100 160 The results presented here indicate, that
Soybean meal 120 160 The DE (kJ) requirement for maintenance (no herbivores such as tilapia do not utilise pro-
energy gain or loss) can be found where the y-axis tein more efficiently than other fish species
rapeseed meal 120 130
is zero. According to the equation above, the (Lupatsch, 2009), but their advantage might
Sunflower meal 120 130 maintenance requirement per day would amount be, that they could be fed lower protein diets
Wheat meal 180 70 to 34.4/0.62 = DEmaint = 55.5 kJ × (kg)0.80. as they are able to consume higher amounts
Corn meal 140 70 The slope of the line in Fig. 1 is a measure of feed compared to carnivores. This fact has
Plant oil - 50 for the efficiency of energy utilization for been highlighted by Lupatsch and Kissil, 2005
growth. For tilapia this amounts to 0.62, or whilst comparing white grouper to gilthead sea-
others 120 30
in other words, 62 percent efficiency. The bream. However, it is important to recognize
estimated composition ( per kg as fed)
reciprocal value 1/0.62 = 1.61 is a measure that even tilapia might reach their physical limits
Dry matter (DM), g 920 920 for the ‘cost of production’ in units of DE (kJ) to consume all the feed to acquire the protein
Crude protein, g 298 405 to deposit one unit of energy (kJ) as growth. needed for maximum growth especially at the
Gross energy, MJ 16.9 19.7 Requirement for protein can be obtained in a juvenile stages (Table 4).
similar manner (Fig 2). The relationship between Using this approach to quantifying energy
Crude lipid, g 29 87
protein intake (x) and protein gain (y) referring and protein demands in tilapia, it is possible
ash, g 72 77
to a metabolic body weight of kg0.70 is as follows: to estimate the biological and economical effi-
Carbohydrates, g 521 351 ciency of different feeds and culture systems.
Digestible energy (De), MJ 11.9 15.3 y = - 0.30 + 0.47x
Digestible protein (DP), g 263 363 References
Maintenance requirement DPmaint (g) = 0.64
DP / De ratio, g / MJ 22.1 23.7 Lupatsch, I., Kissil, G. Wm. and Sklan, D. (2003).
× BW (kg)0.70 and additionally 2.13 units of DP Defining energy and protein requirements of
(g) are needed to gilthead seabream (Sparus aurata) to optimize
table 4: Proposed feeding table for tilapia and expected FCr whilst feeding a deposit one unit feeds and feeding regimes. The Israeli Journal of
high or low protein feed. of protein (g) as Aquaculture - Bamidgeh, 55 (4), 243-257.
Body weight, per fish 25g 150g 300g growth .
Sklan, D., Prag, T. and Lupatsch, I. (2004). Apparent
digestibility coefficients of feed ingredients and
Weight gain1, g / day/ fish 0.70 1.86 2.72
Practical their prediction in diets for tilapia Oreochromis
application niloticus × Oreochromis aureus (Teleostei, Cichlidae).
Voluntary feed intake,
1.0 3.0 4.6 Hence, with Aquaculture Research, 35, 358-364
g/day/fish
the parameters
De requirements, Lupatsch, I. and Kissil, G. Wm. (2005). Feed
10.3 34.0 54.3 obtained energy
kJ / day/ fish formulations based on energy and protein
and protein demands in white grouper (Epinephelus aeneus).
DP requirements,
0.29 0.80 1.20 requirements
g / day/ fish Aquaculture, 248, 83-95.
for tilapia can be
Feed selection (protein) low High low High low High Lupatsch, I. (2009) Quantifying nutritional
calculated and
requirements in aquaculture – the factorial
adapted to chang-
required feed intake , approach. In: New technologies in aquaculture:
1.1 0.8 3.0 2.2 4.5 3.3 ing conditions for
g/day/fish improving production efficiency, quality and
required feed intake,
the duration of environmental management. Burnell G. and Allan
4.4 3.2 2.0 1.5 1.5 1.1 a growth period
% biomass / day G. (Eds). Woodhead Publishing, Cambridge, p
FCr 1.56 1.13 1.64 1.19 1.68 1.22 (Table 1). 417-439.


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and unsustainable use of water and feeds invariably would examine direct pollution and disease risk
lead to contamination in receiving water bodies, as well as the biodiversity impact of tilapia on
disease outbreaks, crop failure, and excessive use indigenous species (a particular concern in warm
of antibiotics. Reflecting the issues surrounding the areas like Hainan Island, the only tropical province
growth of the tilapia industry worldwide, China in China, where wild tilapia can easily survive
stands on the frontline facing the challenge of through winter).
maintaining a steady yield while minimising environ- Some of the existing Chinese tilapia farming
mental and social impacts of aquaculture. regulations and practices do not match inter-
The risks of environmental degradation and national standards, which is critical in meeting
disease associated with the rapid intensification of the growing demand for eco-label certification in

Sustaining aquaculture have resulted in unfavorable assess-
ments of Chinese tilapia in a number of seafood
guides published by NGOs. Chinese tilapia farming
export markets. This could be improved through
building a multi-stakeholder dialogue with effective
knowledge-sharing and information-exchange.

the supply of has been challenged mainly on the following issues:
• The impact on public health from the use of
artificial hormones and antibiotics
Buyers and retailers need to be informed about
progress on sustainability issues through both writ-
ten information and face-to-face communication

Chinese tilapia • Farm effluents and wastes discharged with-
out proper treatment
• The impact on biodiversity from escaped
with producers and suppliers. Guided trips to
farms and plants will not only bring more attention
and acknowledgement to the issues, but also help
tilapia given that tilapia is not an indigenous buyers understand the specific support needs of
by Han Han, Program Manager,
species to China individual aquaculture operations. Their face-to-
Sustainable Fisheries Partnership
• The use of fishmeal in compound feeds and face communication with the policy-makers who

T
its traceability regulate Chinese tilapia aquaculture on the ground
ilapia, the third most internation- • Potential conflicts with other land and water will also enhance awareness of sustainability issues,
ally traded aquaculture product after users thus facilitating the adoption of improved policies.
salmon and shrimp, has been widely More complicated and problematic scenarios Buyers can also encourage the sustainable
farmed in China since the 1950s. With might appear, as global warming will probably sourcing of feeds by asking their suppliers to find
strong governmental support for the research expand the geographic range for some farmed out the ingredients of feed and where it is coming
and development of hybrids and culture technol- tilapia and enhance the survival of escapees, as well from (i.e. the traceability and transparency of raw
ogy, Chinese tilapia aquaculture has grown rapidly as increasing the frequency and severity of extreme materials such as fishmeal).
from the initial stages in the 1960s, to expansion weather events (i.e. floods and droughts). The cur- Given the large number of buyers and suppliers
in the early 1980s, and then to large-scale farming rent challenges in accessing sufficient amounts of it is also essential that stakeholders participate in
and processing in the 2000s. Recent years have clean water will be aggravated as China’s industrial policy roundtables both within and across regions
witnessed a stable annual production of 1.1 development continues its rapid growth. to effectively build consensus around policies and
or 1.2 million mt, about half of the world total. The problems facing tilapia aquaculture in practices and to develop consistency in procure-
Guangdong, Hainan, Guangxi and Fujian provinces China are attributed to a lack of scientific zoning ment standards.
in South China have become the world hub of and regional planning, poor farm-level manage-
farmed tilapia that has been mainly supplied to ment, farmers’ insufficient knowledge of sustainable Where SFP’s Aquaculture
North American and European markets for the practices, and inefficient regulatory enforcement. Improvement Projects can help
past decade. The Chinese government has established regional Sustainable Fisheries Partnership (SFP) is an
and national technology support teams with a independent NGO that promotes sustainable
Tilapia was ranked American’s fourth favorite series of standards to regulate antibiotics usage and fisheries and aquaculture by engaging stakeholders
seafood in 2011. The so-called ‘aquatic chicken’ effluent discharge, as well as investing in research in effective dialogues to mobilise the supply chain
is popular in different forms, including live, fresh, and development regarding tilapia breeding, feed- towards sustainability. The organisation provides
frozen as whole, frozen fillets, gutted, gutted and ing, and processing in recent years. However, the strategic and technical guidance to seafood sup-
scaled, fillets, skin-less, and boneless. In 2010, US improvements have been limited. pliers and producers, helps convene them with
imports of tilapia from China totaled 139,863 mt at other like-minded companies in fishery improve-
a value of $555 million, and increased 22 percent in Exploring solutions ment projects (FIPs) and aquaculture improvement
volume and 36 percent in value over the previous To identify solutions, we first need to both projects (AIPs), and builds consensus around spe-
year. According to the FAO, EU imports of frozen quantitatively and qualitatively identify the prob- cific improvements in policies, marine conservation
tilapia fillet during the first quarter of 2011 posted lems. Unfortunately, when assessing Chinese measures, and fishing and fish-farming practices.
a marginal growth of 3.2% from the same period tilapia’s environmental impact, very limited data SFP involvement in China started in 2007,
in 2010 with China supplying nearly 90 percent of is available to the public. Neither short-term farm- when the organisation began to advise key corpo-
the share to market. Meanwhile, China has seen its level data, nor long-term regional-scale information rate partners on their tilapia procurement policies
export of tilapia making new path into countries is easily accessible and the environmental impact and sourcing, evaluating sources in Hainan and
like Cameroon, Ghana, Congo and United Arab of tilapia farming has never been systematically Guangxi provinces. From 2008 to 2010, SFP con-
Emirates. assessed in China. ducted audits on 10 tilapia farms in six countries,
Although farm-level certification guarantees comparing the three main international stand-
Problematic growth compliance with specific standards at an individual ards: GLOBALG.A.P, Global Agriculture Alliance’s
Such phenomenal growth in both supply and farm this does not provide information about Best Aquaculture Practices (GAA/BAP), and the
demand across the world inevitably faces sustain- environmental impacts and risks at a regional level. International Standard for Responsible Tilapia
ability challenges. Over the past 20 years, a general Given the large number of farms concentrated in Aquaculture developed by the World Wildlife
trend towards intensification in tilapia farming has areas where both agricultural and industrial sec- Fund (ASC/ISRTA). The objective of these audits
led to an increasing dependence on formulated tors share water resources it is clear that regional was to identify similarities in criteria and areas
feeds and freshwater supply. Poor management assessments are highly desirable. Such studies where the standards differed. The benchmarking


EXPERT T●PIC

project included four tilapia farms in China. These identify the key problems and causes related to in April, 2011. Over 40 farmers, processors, tech-
farms represented both small- and commercial- water management. nicians and government officers attended the
scale production facilities utilising two different The second project is an assessment of the workshop. Participants found the workshop very
production systems (pond and cages). Aside from regional environmental impacts of fish farm clusters, informative and helpful. This enhanced the produc-
identifying similarities and differences among criteria which will be jointly conducted by SFP and Hainan ers’ awareness of increasing demands for certified
and requirements used by the three standards, Research Academy of Environmental Sciences, the sustainable seafood from overseas markets, thus
this project also identified outstanding issues in the leading environmental research institute in Hainan. further facilitating the engagement of Chinese
farms, which most producers were able to address The study will examine the potential for regional stakeholders into a supply-chain dialogue around
as a result of the trial audit. To date, all four farms scale improvement by looking at carrying capacity sustainability.
are now certified under one or more of the com- and the potential for zoning in a specific area. SFP is currently working with local institutes of
mercial aquaculture standards. As more first-hand data becomes available aquaculture and environmental sciences to identify
SFP is widely acknowledged for its expertise (along with a more in-depth understanding of and evaluate both qualitatively and quantitatively
by stakeholders in Chinese tilapia, including key existing policies and management measures), the the environmental impacts of tilapia farming in
US and European buyers and retailers, as well as AIP will establish a working group that convenes Hainan. This includes an ecological study as well as
producers and processors in China, aquaculture the key buyers, suppliers and producers along the socio-political analysis to advise local governments
institutes, industry associations, and local Chinese Chinese tilapia supply-chain to share the scientific and industrial associations about how to efficiently
governments. Given the high level of trust that SFP findings. The AIP will then form a multi-stakeholder address the environmental issues associated with
enjoys with the tilapia supply chain it was appropri- policy roundtable to further discuss the problems tilapia farming in Hainan. The preliminary results will
ate that a tilapia Aquaculture Improvement Project and solutions. The AIP participants will eventually be shared with key stakeholders at the Aquaculture
(AIP) was officially launched in 2011. agree on the actions and timetables necessary to Policy Roundtable this fall in China.
SFP has now initiated two research projects achieve the sustainability objectives defined by SFP is also developing partnerships with
to assess the impact of tilapia farming on the the group. SFP will play a leading role in engaging Chinese universities and large feed manufacturers
external environment. The first project, started stakeholders, providing scientific advice and facilitat- to improve feed sourcing for tilapia farming in
in April 2011, involves monitoring water qual- ing communication. China. This work is to be undertaken through
ity on selected farms in Hainan province, and research projects on improving feeding efficien-
was undertaken by the Hainan Institute of Up-to-date progress cy and developing alternative feeds with fewer
Aquaculture. Dozens of water quality param- SFP has worked closely with local tilapia associa- impacts on wild fisheries.
eters such as chemical oxygen demand (COD), tions to assess different tilapia standards that are
nitrogen and phosphorus content, and heavy available in the market. A workshop introducing More InforMatIon:
metals were analysed for five farms over two three international standards for tilapia farming, i.e. Sustainable Fisheries Partnership
croppings (10 months). The study helped BAP, GlobalGAP, and ASC, was held in Haikou Website: www.sustainablefish.org


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