The document provides an overview of finfish culture systems and practices. It discusses extensive, semi-intensive, and intensive systems and their key characteristics. Pond culture is described as the earliest form of aquaculture, with details on site selection and layout. Other culture methods covered include cage culture, pen culture, and running water culture using raceway systems. Integrated fish farming and culture of cold and warm water finfish are also summarized.

1. FINFISH CULTURE SYSTEMS
& PRACTICES
BY WESONGA O SAMWEL
SNAT/FAS/M/002/20
2020

2. INTRODUCTION
• Fish with fins, as opposed to shellfish or hagfish – finfish
• The science of rearing/farming these fish in aquatic environment or in
settings that resemble them – finfish aquaculture
• Finfish aquaculture comes with many options
• Farming systems (land based, water based, recycling & integrated)
• Intensity (extensive, semi-intensive and intensive)
• Scale (small/large)
• Environment (fresh, brackish and marine waters)
• Cold and warm water culture

3. EXTENSIVE, SEMI-INTENSIVE AND INTENSIVE
SYSTEMS
• Brought about by the continuum of increasing intensity
• Also be referred to as open, semi-closed and closed systems respectively
• Extensive systems rely entirely on natural ecological processes
• Semi-intensive systems rely largely on nature to provide the three basic ecological services of
proper temperature, sufficient oxygen, and waste removal with little human intervention
• In intensive systems there is total manipulation/intervention by human.

4. CONT’D
• For aquaculture, intensification implies a number of things:
• Stocking density
• Management
• Energy inputs (invested in each kg of production; feeds, fertilizer, lime, pesticides &
manipulation of the environment in line of aeration, pumps, filters)
• Production – financial returns
• Engineering design and layout – not well laid out to very well engineered system
• Species used – monoculture/polyculture, monoculture, monoculture
• Feeding regime – none, regular feeding of high quality feeds but depending on stocking
densities partial feeding practiced, total feeding of high quality formulated feeds
• Quality and size of the product – not reliably good product with variable sizes, good
product with fairly uniform sizes, good quality product with uniform sizes

5. 500 and 1500 kg/ha/year (10%) 3 tonnes/ha (70%) 10 000 to 80 000 kg/ha/year
Oceans, lakes, rivers, dams earthen ponds, dams tanks, holding units, cages
Tilapia, catfish, C. Carpio tilapia, catfish, C. Carpio rainbow trout, salmon catfish
• Poly/monoculture poly/mono monoculture
Disadvantage-
• poaching: - many people feel they have every right to catch or harvest any aquatic animal from a
natural or public body of water
-Predation
Diseases increases with intensity
EXTENSIVE SEMI-INTENSIVE
INTENSIVE

6. AQUACULTURE PRACTICES
• Freshwater culture; fish ponds, fish pens, fish cages or, on a limited scale, in rice paddies
(Tilapia, catfish, trout, carps)
• Brackishwater culture – done mainly in fish ponds located in coastal areas
Common species include milkfish (chanos chanos), mullet (mugil sp.)
• Mariculture – involving extensive culture and producing fish/shellfish
(Sea bass, grouper, red sea bream, yellowtail, rabbitfish)

7. PONDS
• The breeding and rearing of fish in natural or artificial basins
• Is the earliest form of aquaculture with its origins dating back to the era of the yin dynasty
(1400-1137 b.C.)
• Carried out mostly using stagnant waters but can also be used in running waters especially in
highland sites with flowing water.
• Commonly raised species in freshwater ponds are the carps, tilapia, catfish, snakehead, eel,
trout, goldfish, gouramy, trout, pike, tench, salmonids

8. SITE SELECTION.
• The first step guaranteeing the eventual success of any aquaculture project
• Forms the basis for the design, layout, and management of the project (SCSP, 1982a)
• Guidelines for the selection
• Soil quality; preferably clay-loam, ph 7 and above
Land elevation water elevation
• Water supply vegetation
• Accessibility labour

9. LAYOUT
• Depends on species, size and shape of the area
• Layout determines size and number of the pond and the position of water canals and other pond compartments that
mutually complete each other
Stocking, feeding, fertilizer, rate of water and species type are dependent on one another

10. CAGE CULTURE
• Practical approach to increase the aquaculture
production
• Involve fish husbandry in enclosure in large water
bodies like lakes, dams, swamps or tanks
• Cages usually are made of a rigid frame covered with a
mesh material through which water can readily flow
but fish cannot escape
Vary in
• Size; from about 30 or 40 ft3 to several hundred cubic
feet.
• Shapes; cylindrical, cubical or basket like
• Materials used; non-corrodible types of wire, plastic
coated wire, nylon, plastic and even bamboo
• ; Durable, strong, light, allow passage of fish waste
and water (complete exchange of water volume every
30 to 60 seconds), resistant to fouling and readily
available
• Types ; floating at the surface, just submerged or
made to sit on the bottom

11. CONT’D
Location.
An ideal location should have
• A flow of a slow current of 1 - 9 m/minute
• Weed free shallow waters
• Moderate wind and wave action
• Easy accessibility
• A ready market

12. PEN CULTURE
• A fixed enclosure in which the bottom is the bed of the
water body
• Installed in shallow waters
• Bigger and cheaper to cages
• Species; yellow tail (seriola quinqueradiata), red sea
bream (pagrus major), file fish (monacanthus cinhifer)
and rock fish (sebastes marmoratus)
• Shallow lagoons, sheltered and other inter-tidal and
sub-littoral coastal areas are generally suitable for pen
culture
• Types;
• Rigid pens
• Flexible pens
• Outer barrier nets
Site characteristics
• Site must be sheltered as much as possible against
high winds.
• The best site is on the leeward side of the prevailing
winds with moderate flow of current especially in a
place where current in overturning.
• The site chosen should have low tidal amplitude.
• Depth of the area should not be less than 1 meter
during lowest water level
• Water with stable ph slight variation is best.
• Muddy clay and clay - loam soils are best types of
bottom soil.

13. RUNNING WATER CULTURE
This practice started in the early 70s
Applied mostly in highland sites,
otherwise most aquaculture practices
are done in stagnant water.
Fish in stagnant water takes longer to
reach marketable size.
Principles of running water culture
• Requirement of the large volume of
water
• Application of rapid water changes
• Plentiful supply of nutritious feed
• Heavy stocking of the cultured species
ADVANTAGES
• SHORT CULTURE PERIOD
• HIGH PRODUCTION
• ENABLES HIGH STOCKING RATES
• THE ABUNDANT WATER BRINGS OXYGEN AND
WASH AWAY WASTES
DISADVANTAGES
• HIGH DEPENDENCE OF ARTIFICIAL FEEDS
• LARGE VOLUME OF WATER
• ENERGY IS WASTED IN SWIMMING AGAINST
CURRENTS
• EXPENSIVE

14. RACEWAY CULTURE SYSTEM
• Typically long, narrow, rectangular trenches in which
water is flushed through continuously
• Stocking density much higher than static water
• Water should flow evenly through the system to
eliminate areas of poor water circulation where waste
materials or sediment may accumulate
• Large quantities of good quality water
• Fish are dependent on artificial diet
-Higher protein content and more complete vitamin and
mineral supplements
• The economic costs and management requirements are
expensive
Types; earthen raceways, concrete raceways, metal
raceways andfiberglass raceways
Shapes;
1. Circular
• A concrete structure which slopes down to a vertical
placed drain pipe at the center, the outlet which flushes
the water level
• Water is introduced through a pipe running radially
towards the center having four or more nozzles
spraying water simultaneously to create a whirling
motion with an even current
• A screen inform of a sleeve is fitted on the drainage
pipe to guard the orifice

15. • THE ADVANTAGES OF A CIRCULAR RACEWAY
ARE:
• 1) ECONOMY IN THE USE OF WATER;
• 2) UNIFORM WATER CIRCULATION
THROUGHOUT THE RACEWAY;
• 3) UNIFORM DISTRIBUTION OF FISH INSTEAD
OF THEIR CONGREGATION AT THE HEAD
END;
• 4) SELF CLEANSING EFFECT CAUSED BY
CENTRIFUGAL MOTION OF THE WATER.
•
• THE DISADVANTAGES OF A CIRCULAR
RACEWAY ARE:
• 1) SUFFICIENT WATER PRESSURE HAS TO BE
MAINTAINED FOR SUPPORTING A CIRCULAR
MOTION;
• 2) FLUSH TREATMENT OF DISEASE CONTROL

16. 2. RECTANGULAR Advantages
• Bottom accumulation support a growth of
bacteria, algal, protozoans and insect larvae,
which serve as fish food; frequent cleaning
not necessary
Disadvantage
• Accumulations at the bottom release toxic
gases; organic decomposition affect the fish
taste
3. Another shape is hexagonal

17. RECIRCULATING SYSTEMS FISH CULTURE
• Fish culture applied by re-using the water that has been
once utilized to produce fish
• Practiced in places where there is scarcity and shortage of
water
• Water already utilized by fish is not recommended for
further fish culture because it has;
Organic waste
Zoo + phytoplankton
Parasites, bacteria and other pathogens
Toxic materials and gases like ammonia,
hydrogen sulphides
Metabolites and other repressive factors
Hence most of these factors have to be eliminated before re-
use
• To do this, the complicated system is divided into
small parts called unit processes that corresponds to a
specific treatment process.
• The design and layout of the system depends on the
scale or intensity of the practice, cost and the level of
technology
• The simplest flow system have;
a). Filtration
• The water moves from the central fish culture tank and
flows through a filtering system that remove the
settleable, fine, dissolved and suspended waste solids.
The solids are produced as uneaten feed, feed fines,
fish fecal matter and algae. Screen filters and
expandable granular media filters are used

18. 2. Convert the ammonia to nitrate (biofiltration)
• The water flows to some form of biofiltration, such as
a trickling tower, bead filter, fluidized sand filter, or
moving bed bioreactor
• Ammonia is converted to nitrate by autotrophic
bacteria. The process of bacterial driven ammonia
removal in a biological filter is called nitrification
• Consists of the successive oxidation of ammonia to
nitrite and finally to nitrate
• Nitrosomonas:
Nh4
+ + 1.5o2 → no2− + 2h+ + h2o (1)
• Nitrobacter:
No2− + 0.5o2 → no3− (2)
• Overall:
Nh4
+ + 2o2 → no3
- + 2h+ + h2o (3)
3. Remove carbon dioxide and add oxygen
• At high loading densities, a carbon dioxide stripping
column is then required to remove excess CO2 and
aerate the water to saturation. At high stocking density,
an oxygenation device is installed
4. If required; disinfect the water before
returning it to the culture tank
• UV or ozone system is added to disinfect the returning
water stream as part of a biosecurity program or where
extremely high-quality water is required.

19. INTEGRATED FISH FARMING
• It is a mixed farming practice involving the culture of fish
alongside crops or live stock.
• Serves as a model of sustainable food production
• The waste products of one biological system serve as nutrients
for a second biological system
• This polyculture increases diversity and yields multiple
products.
• Water is re-used through biological filtration and recirculation
• For example certain areas, paddy fields remain flooded with
water for a period of 3-8 months in a year, during which some
growth of fish is easily possible
• Fish perform tillage; destroy weed and insect that cause damage
to the paddy plants, thus increasing paddy production
• Common in italy, japan, malaysia and several african countries
• Fish species must be able to thrive in shallow areas,
tolerate relatively higher temperature and turbidity.
E.G. Certain tilapia and carps
Types
• Fish farming with agriculture; rice-fish culture,
poultry-fish integration, horticulture-fish system,
mushroom-fish system

20. Advantages of integrated
• Establishment of a man-made ecosystem without any wastes
• Increasing the food supply for the mankind
• More job offers

21. CULTURE OF COLD AND WARM WATER
FINFISH
• Cultivation of aquatic organisms through human intervention that involve some control
over stock can be done over different temperature environments
• Temperature is a necessary input for several aquaculture growth models
• Different finfish species work best at different temperatures (optimal)
• Small changes in average temperature may have significant effect on growth rates.
• Eurythermal fish are able to withstand wide ranges of temperature fluctuations. (Opposite
- stenothermal)

22. In most types of aquaculture temperature cannot be controlled and depends upon the amount
of solar radiation, air temperature, or the temperature of water passing through the culture unit

23. COLD WATER SPECIES
• Finfish and invertebrates whose thermal optimum for growth is below 20◦C are classified
as coldwater species
• Examples of commercially important aquaculture species within this group include
• The marine atlantic salmon (salmo salar)
• The freshwater rainbow trout (oncorhynchus mykiss)
• Rainbow trout are close relatives of the pacific salmons.
• Can tolerate 0-20◦c but their optimum temperature for growth is about 10 to 16◦c
• They require relatively high oxygen levels (>5 mg/l)
• Tolerate only low levels of ammonia (<0.0125 mg/l unionized).

24. Rainbow trout (Oncorhynchus mykiss)Trout culture is commonly practiced primarily to
meet the stocking requirements of streams, lakes
and reservoirs for sport.
The culture practices involves
• Spawning (3-4years, spring (Feb –mid March), 800-2000 eggs/kg of body
weight)
• taking quality eggs from healthy fish,
• incubation of eggs,
• rearing of young fries in nursery ponds,
• raising of fingerlings in growing ponds and
• producing yearlings in raceways, circular ponds

25. The following key features should be kept in mind for
establishing a new trout farm:
(1) A gently sloping site is better
(2) adequate supply of water
(3) range of water temperature should be preferably between 5-20 °C
(4) water should be almost free of suspended or finely divided solids.
(5) water should be neutral or slightly alkaline.
(6) well oxygenated water (dissolved oxygen above 7 mg/l) is the prime
requirement for trout farming.
(7) frequency of water exchange according to the size of fish should be kept in
mind.
(8) the ponds /tanks/raceways may be stone walled solid concrete

26. Cool water species
• Species whose optimum temperature is around 20◦C
• Currently there are fewer commercially important aquaculture
species in this category.
• The striped bass (morone saxatilis),
• Yellow perch (perca flavescens), and
• European perch (perca flaviatilis)
• For the striped bass the optimal temperature is reported to
be 15 to 17◦c (kohler 2000).
• The optimal temperature for yellow perch is 22 to 24◦c with
an upper lethal limit of 30◦c (hart et al. 2006).

27. WARM WATER SPECIES
• Many important aquaculture species are considered warmwater species
• Optimum temperature around 30◦C.
• Species
• Common carp (cyprinus carpio),
• Channel catfish (ictalurus punctatus),
• Sea bass (dicentrachus labrax),
• Gilthead sea bream (sparus aurata),
• Yellowtail (seriola quinqueradiata

28. • Tend to have a greater tolerance for lower dissolved oxygen (DO) levels
• This is logical as warm water holds less oxygen
• They also tend to tolerate higher levels of un-ionized ammonia
Tropical species
Is a sub-brunch of warm species
Optimum temperature is >30◦C
E.G. Tilapia, with an optimum temperature of 29 to 31◦C
• <18◦C they get sick easily as their immunocompetence is severely compromised at
temperatures below their optimal range.
• <10 to 12◦c they normally die within a few days as enzyme systems cease to function.
• >25◦c, tilapia are very tolerant of handling low oxygen levels and high ammonia levels

29. Types of systems and practices used in warm water
aquaculture
• Notable systems and practices are
• Recirculation aquaculture systems,
• Earthen ponds, concrete pond, levee pond
• Cages and surface tanks

30. SUMMARY
Cold water fish Warm water fish
Can not tolerate temperatures above 20 to 25 degrees-C Can not reproduce at temperatures below 20 degrees-C
Can not grow at temperatures below 10 to 15 degrees-C
Tropical species will die at temperatures of 10 to 20
degrees-C
Tropical species will not grow at temperatures below 25
degrees-C
thermal optimum for growth is below 20◦C Optimal temperature of around 30 degrees C
Low ammonia tolerance Moderate ammonia tolerance with highest tolerance in
tropical species
High protein requirements Moderate to low protein requirement
Dissolved oxygen >5mg/l Dissolved oxygen >2mg/l, for tropical species is >1mg/l

31. Temperature vs climate change
• Temperature change is one of the most consequential effects of climate change on
aquaculture
• Rising temperatures due to global warming are likely to cause fluctuations in the thermal
dynamics of species living in cold water environments
• Increasing stratification,
• Decreasing nutrient circulation, and
• Implications for primary production and hence higher trophic levels
• In aquaculture, this will affect growth rate, time to market and thereby economic return of
both cold and warm water culture
• It can also influence immune functionality, life cycle of pathogens, reproductive cues, larval
survival, diet digestibility, gene expression, metabolic rate, enzyme functionality and
behavior