fish farming

A brief history of fish farming in Kenya

Aquaculture industry in Kenya has greatly grown over the last few decades. Promotion of aquaculture started in the early 1920s as a subsistence means of supplementing protein sources in the rural areas. This was a non-commercial approach and it was promoted only as a family subsistence activity. This has however changed over the years with the government putting a lot of effort and resources in promoting aquaculture as a business. Many entrepreneurs s have now invested in commercial aquaculture ventures.
Aquaculture activities in Kenya involve the production of tilapia (mainly Oreochromis niloticus), the African catfish (Clarias gariepinus), the Rainbow trout and a variety of marine species though to a limited extent. The tilapias and catfish production is mainly done under semi intensive systems using earthen ponds while the Rainbow trout production is done in intensive raceways and tank systems. The Tilapia species constitute the largest portion of aquaculture production in Kenya.
Aquaculture in Kenya can be divided into two broad divisions, i.e.

• Marine aquaculture and
• Fresh water culture.

Although Kenya has a long coastline bordering the Indian Ocean, and therefore great potential for marine aquaculture, this is yet to realise any meaningful development and the resources remain largely unused.
Fresh water aquaculture dominates fish farming in Kenya and can be divided into:

• Cold water culture involving culture of rainbow trout (Oncorhynchus mykiss) in highland areas and
• Warm water culture involving the culture of Tilapine fishes, the African catfish, common carp and a variety of ornamental fishes in low land regions of the country.

1.1 Importance of fish farming

Source of good quality protein rich food
a) Source of income to farmers and revenue to government
b) Creates employment opportunities
c) Contributes to National food security
d) Optimizes use of water resources

1.2.1 Aquaculture investment opportunities in Kenya

Some potential areas of investment in commercial aquaculture:

i).            Integrated aquaculture Aquaculture can easily be integrated with conventional crop and livestock farming. The management techniques and inputs employed are similar to those that crop and livestock farmers are familiar with. Integration has a lot of benefits for farmers. In addition to the production of fish for consumption or sale, it increases efficiency in use of available production resources by allowing for recirculation of nutrients among different production units. This provides opportunities for diversification on crop and livestock farming and can put to productive use otherwise idle land resources

ii).          Cage culture This can be done in rivers, water reservoirs, lakes and the ocean. The advantage here is that more benefits can be generated from such water bodies and yet the technology and the capital input do not have to be demanding.

iii).         Bait cultureThere exists a very big market for bait fish (juvenile Clarias gariepinus and Chanos chanos) for the Nile perch capture industry in Lake Victoria and Tuna fisheries of the Indian Ocean. The technology for the culture of the bait fish exists locally among aquaculture experts and many farmers in the Lake Victoria region are already doing it.

iv).       Ornamental fish cultureThere are only a handful of ornamental fish producers in Kenya. Resources for culture of both marine and fresh water species are available in Kenya. Potential markets for the ornamental fishes include local cities, the Africa countries, Europe and Asia.

v).         Integration with livestock farming in ASALFish could be stocked in water pans meant for livestock watering. This will increase the benefits accrued form such water bodies by diversifying sources of income and increasing security for quality food for livestock farmers in such areas.

vi).       Capture-based AquacultureThis can be done in the many water reservoirs in the country. These include domestic water reservoirs, irrigation reservoirs and the hydro electricity reservoirs. Capture-based Aquaculture involves stocking of such reservoirs with appropriate fish species of commercial value which is later harvested when mature. This can have an overall effect of increasing the fisheries resource base and therefore food security and incomes to fishers.

Any or a combination of the above can lead to attractive profits if well planned and thought out. For an investor to opt for any of these enterprises, it is important for the decision to be based on proven facts. This calls for thorough prior planning.
1.0 Considerations before investing in fish farming
When starting fish farming, thorough planning before any investment is made is very important. Planning will involve a detailed evaluation of both the biological and socio-economic, aspects of the proposed activities. The technical requirements for fish production must be satisfied for the fish farmer to harvest a crop that meets both his economic and social goals.
It is therefore essential to ascertain that your aquaculture business idea is realistic.

Ask whether:

1)     There are adequate and profitable markets for proposed product(s)

It is very important for those who want to go into fish farming to do economic evaluation of their proposed investment. This will tell them, among other things:
a) How much one needs to invest
b) How one should invest and
c) Whether one will make a profit in the long run
Economic evaluation of a new fish farming venture could be complex and therefore, the best way is to contact an aquaculture economics expert from the Ministry of Fisheries Development to assist.

2)     You can access adequate essential support services
3)     Your proposed undertaking meets all the environmental, social and legal requirements.

Integrated Systems;

Manure application can be made easy by placing animal production units adjacent to or over the fish ponds so that fresh manure can easily be delivered to the pond on a continuous basis. This also allows the feed wasted by the animals to fall into the fish pond and utilised by the fish. Effective and safe manure loading rates are maintained by having the correct number of animals per pond surface area.

a)   Chicken/fish farming:

Maximum tilapia yields are obtained from the manure output of 5,000 to 5,500 chickens/ha, which deliver 100 to 113 Kg (dry weight) of manure/ ha/day. Several crops of chickens can be produced in one fish production cycle.

b)   Duck/fish farming

Ducks are grown on ponds at a density of 750 to 1500/ha. The ducks are raised in confinement, fed intensively, and allowed a small portion of the pond where they forage for natural foods and deposit their manure. Ducks reach marketable size in 10 to 11 weeks and therefore staggering production cycles is needed to stabilize manure output.

 c)   Pig/fish farming

Approximately 60 to 70 pigs/ha are required to produce a suitable quantity of manure (90 to 100 pounds of dry matter/acre/day) for tilapia production. The pigs are usually grown from 44 to 220 pounds over a 6-month period. In cultures and religions where pigs are considered unclean, used of pig manure might reduce the marketability of the fish.

 d)   Rice cum fish farming

Various methods of integrating rice and fish are applied. The common used in is to stock fish when the rice field is being filled with irrigation water. Specially designed ponds can be used to allow for the two cropping. This can be done by digging trenches within or around the paddy for fish.

Aquaculture Production Systems

1.1 Aquaculture Production Systems

• Extensive systems
• Semi-intensive systems
• Intensive systems

Aquaculture, compared to crop and animal farming, is much more diverse and varied. There are many different species that are cultured each with different ecological requirements. They therefore have different feeding and breeding requirements as well as water quality. Production systems have therefore been developed to meet both the economic needs of the producer and the requirements of the species to be cultured.

Depending on the planned level of production and the resources available, the producer will make a choice from the following:

i). Extensive systems

In these systems little or no input is used in the production. Fish are stocked in cages, still water earthen ponds and other water impoundments (for example reservoirs) and left to fend for themselves. Low stocking densities and thus low yields characterize the systems. The main cultured species are Tilapines (e.g. Oreochromis niloticus), catfish e.g. Clarias gariepinus and Cyprinus carpio. These are low input-low-output production systems. Majority of the small scale, subsistence fish farmers in rural Kenya fall in this category. Production in these systems ranges between 500 and 1500 Kg/Ha/year.

i). Semi-intensive systems:

These systems form the bulk of aquaculture production in Kenya. In these systems still water earthen ponds and cages are used as holding units for fish culture. Still water pond culture uses the natural productivity of the water to sustain the species under culture. However to enhance productivity, the ponds are fertilized using both chemical and organic fertilizers at varying proportions to enhance natural productivity. Exogenous feeding using cereals bran and other locally available feeds is done to supplement pond productivity. Polyculture of Oreochromis niloticus, Clarias gariepinus and Cyprinus carpio is practiced with various combinations of species.

Commercial production in these systems range between 1 - 3 Kg/m²/year depending on individual farmers management level. Some farmers in western Kenya have achieved production levels of between 6-10Kgs/m²/year with tilapia and catfish.

ii). Intensive systems:

In these systems water flows in and out continuously (flow through). This allows higher stocking densities. The systems require good supply of good quality water. Less land is required to produce the same quantity of fish as compared to extensive and semi intensive systems.
The systems employ mainly raceways, various types of tanks and floating cages as holding units. In these systems, more fish are produced per unit area by complementing or substituting the natural productivity in the culture units by exogenous feeding using complete feeds (the feeds are specifically manufactured for the species under culture) and water aeration. Such operations require high initial capital investment and high operational cost. They are mainly suited for high value fish like the Rainbow trout.
Production in such systems in Kenya range from 10 to 70 Kg/m²/year. This depends on the management levels employed by individual producers. This production can go higher with better management and quality feeds.

1.1 Issues to consider for pond culture of fish:
a) Fish to be produced
Different fish require different ecological conditions and production techniques to grow.
The choice of what to produce will therefore be guided by:
a)   Market preference
b)   Ecological requirements of the fish
c)    Production technology of the fish
d)   Resources available to produce the fish
b) Proposed farm site:
Fish farming is a long term investment and therefore it is important to know land tenure system of the site. Conflicts may arise regarding land ownership.
The topography of the land will determine whether it will be possible to construct fish production facilities and also the cost of construction. The accessibility of the site throughout the production period is very important. Availability of power and other essential infrastructure should also be considered. The location of the site in relation to the market is also important.

a) Water:
Fish are aquatic animals. Enough clean water is required throughout the growing period. Will the water be enough to last the entire growing period? Is it of good quality? Water quality refers to consideration for salinity, temperature, dissolve oxygen, acidity/alkalinity (pH) suspended particulate matter. Water that is good for livestock and human beings is good for fish farming. It must not contain excessive dissolved and suspended solids or toxic substances.
b) Soil:
Where earth ponds will be used to grow fish, soils with good water retention ability are preferred. Where the soils are too porous, then the option of using pond liners or tanks can be considered. Note that this will increase the investment cost. Some soils are acidic and this needs to be corrected through liming. Lime may not be cheap.

a) Fingerlings:
It is good to know the source of good quality fish seeds (fingerlings). Some stunted or sick fish may be sold as fingerlings. The bad quality fish cannot grow to acceptable market sizes and may not even be acceptable in the markets. Sourcing fingerlings from certified sources is important.
b) Fish feeds:
Fish feeds come in various forms e.g. powder, pellets, marsh or granules. Commonly used feed ingredients include maize bran, rice bran wheat bran, fresh water shrimps etc. Farmers should always consult fish feeds experts for correct information.
Availability of quality fish feeds is critical to the success of the enterprise. Feeds form the highest single cost entity in fish farming - up to 60% of the enterprise operational costs are incurred on feeds. Feed requirements in fish vary with age. Young or juvenile fish require a higher protein content feed (about 35% - 40%) while adult fish may require 25% - 35% protein rich foods.

Fish Farm Planning:

Fish farm Planning

Planning a fish farm is an important step in the farming investment. You need to plan and design access roads, buildings, hatcheries, production ponds, etc.
The final size of a fish farm is determined by:

• Amount of water available
• The land available and usable for fish culture
• The technology to be employed; Intensive systems require less land compared to semi intensive systems, to produce the same quantity of fish
• The target production
• Capital available for investment

The number, size and the shape of ponds will be determined by:

• Land size
• Topography of the land
• Intended use of the pond
• The species to be produced
• Frequency of harvest
• Target quantity per harvest
• Whether juvenile production is intended etc.

For these reasons it is not always possible to give general recommendations on the sizes and shapes of earthen ponds. However, rectangular ponds are easier to manage.

Earth Pond Design and Construction:

Once the site has been identified, surveyed and the producer has made decision on the number and sizes of ponds that will be needed when the farm is fully operational, it is time to make decision on designs of the ponds.
The importance of proper designs, construction and the need for involvement of experts during the process of construction of fish ponds cannot be belittled.
Ideally, a good pond should be designed in such a way to allow total control of;

• What gets in or out
• When it gets in or out
• How it does this
• How much gets in or out
• Rate of getting in or out

During the process of designing ponds, decisions on the following should be made:

• Total area of the pond water surface needed
• The length and the width of the pond water surface
• The water depth and the total pond depth at both the deep and shallow ends
• The slope of the dykes and the pond bottom
• The size of the free board
• The width of dykes

The diagram below gives the relationships between various pond dimensions for a 300m² pond based on the assumptions that:

Pond Construction Costing

Through experience in Kenya, one pond of 100 m² will take 15 people about 8 days to complete, working 8 hours a day.
This will cost 15 x 8 x KShs X (X = agreed wage per day)
Ponds should be fitted with screens at inflow and outflow structures to prevent invasion by wild stock.
NB: It is always very important to consult an aquaculture farm planning and pond construction experts for assistance.

Steps in pond construction:

1.      Mark out the area that the pond will occupy using wooden pegs and strings and then remove all the vegetation.

2.      Remove the top soil and keep it in a good location close to the site. It will be used to cover the pond bottom and the dyke tops to enhance fertility. Remember that if the soil is kept far away, this will increase the cost of pond construction since the soil will need to be brought back

3.      Clear the area within the pond limit of all vegetation including the area within 10 m of dykes and pond structures and any access, water supply or drainage area.
4.      Establish a Temporary Bench Mark (TBM). This will allow you to determine and check by use of levelling equipment (e.g. spirit level) the elevations of the dykes, canals and other structures. The TBM should be set and permanently fixed in a protected location during the whole construction period.

5.      Using level equipments (e.g. spirit level), measuring tape, pegs and strings, mark out:

• The dykes
• Dyke slopes
• Inner and outer toes
• The pond bottom

6.      Using the determined pond depths and the actual elevations of the site, determine which areas need digging and which need filling. This is very important because it eliminates unnecessary movements of soil and thus keeps the construction cost at a minimum.
7.      Dig out the soil from the ‘dig’ areas and place it on the ‘fill’ areas. Most of the fill areas will be on the dyke position.




8.      Once the soil is placed on the fill area, make sure that this soil is properly compacted. To achieve good compaction, place soil in layers not exceeding 15 cm in height and compact back to at least 10 cm. When constructing dykes, soil layers are place 20 cm inside on top of each other to reduce amount of work during dyke cutting.

Farming of Tilapia in Ponds;

Tilapia farming involves the culture of the following species:
(i)             Oreochromis niloticus
(ii)           Oreochromis mossambicus
(iii)          Oreochromis aureus
(iv)         Oreochromis spilurus
(v)           Oreochromis andersonii
(vi)         Tilapia zillii.
(vii)        Tilapia rendalli

I). Feeding Habits

Tilapias are heterogeneous (i.e. varied) in their feeding. They are hardy (tough, resilient), have rapid growth, and have ability to consume and efficiently assimilate a wide variety of foods.


II). Maturation
In natural water bodies, tilapias mature in about two to three years. Under culture they tend to mature early. Sexual features distinguishing males from females are clear when fish mature (about 15 cm in Tilapia zillii and 10 cm in Oreochromis niloticus). Males have pointed papilla while females have flat horizontally slit papilla.

III). Fecundity
Fecundity refers to the number of eggs produced by a fish in a spawn. This applies well for monocyclic species, that is, once a year breeders. Tilapias are polycyclic (many times breeders) and their ovary may contain eggs at different stages of maturity.
Table 1: Some characteristics that differentiating substrate brooders (Tilapia) and mouth brooders (Oreochromis):

Characters	Tilapia	Oreochromis
Fecundity	high	Low
Egg diameter (mm)	1-1.5	up to 5.0
Yolk percentage	less than 25%	up to 45%
Yolk colour	pale yellow	Orange
Size of fry at feeding	5-6 mm	9-10 mm
Courtship	prolonged (monogamous)	brief (polygamous)
Juvenile mortality	high	Low
Longevity (life span)	up to 7 years	over 9 years

Environmental Requirements

a) Optimal Temperature:
Various species and strains of tilapia differ in tolerance to low temperatures, but growth is poor at water temperatures below 16^OC and death occurs from temperatures below 12^OC.Most will not feed or grow at water temperatures below 15^oC and will not spawn below 20^OC. The normal water temperature should be between 20 to 30^oC. Higher temperatures will result to fish death.
b) Optimal Dissolved Oxygen (DO):
Tilapias are able to tolerate low levels of dissolved oxygen. Usually, well fertilized ponds will have low levels of oxygen early in the morning. Night activities are dominated by respiration and decomposition which reduce DO. Larger fish are less tolerant than juveniles. This could be due to the difference in their metabolic demand. The optimal DO for tilapia culture is 4 mg/litre (50%) and should not go below 2.3 mg/litre.

c) Salinity
All tilapia are tolerant to brackish water. The Nile tilapia is the least saline tolerant of the commercially important species, but grows well at salinities of up to 15 ppt. The Blue tilapia grows well in brackish water up to 20 ppt salinity, and the Mozambique tilapia grows well at salinities near or at full strength seawater.
d) pH
pH refers to hydrogen ion concentration levels. Tilapia can survive in pH ranging from 5 to 10 but do best in a pH range of 6 to 9.

e) Ammonia
Massive tilapia mortality will occur within a few days when the fish are suddenly exposed to water with unionized ammonia concentrations greater than 2 mg/L. Prolonged exposure (several weeks) to un-ionized ammonia concentration greater than 1 mg/L causes deaths, especially among fry and juveniles in water with low DO concentration.

f) Nitrite
Nitrite is toxic to many fish and chloride ions reduce the toxicity. Tilapias are more tolerant to nitrite than many cultured freshwater fish. In general, for freshwater culture the nitrite concentration should be kept below 27 mg/L.

Sources of Fingerlings:

Some important sources of fingerlings include:

a) Government fish multiplication centers e.g.
i)        Sagana at Sagana in Kirinyaga County
ii)      Kiganjo trout centre in Nyeri County
iii)     Chwele fish farm at Chwele in Bungoma County
iv)   Wakhungu fish farm at Bumala in Busia County
v)     Kisii fish farm in Kisii town
b) Lake basin development authority fish farms e.g.
i)                    Kibos fish farm in Kisumu County
ii)                  LBDA Chwele fish farm Chwele in Bungoma County
iii)                 Yala fish farm in Siaya County
iv)               Alupe fish farm in Busia County
c)    Selected and certified fish farmers .(a list is to be found at Ministry of fisheries Development offices at County levels)
d)    Farmers can produce own fingerlings (They need to work with seed production experts for advice)

Transport of fingerlings and stocking:

Factors that affect live fish transportation include:

• Distance and mode of transportation
• Age, size and weight of fish,
• Temperature of the water and nature of transport container.

Prior to fish transportation, fish require to be starved for two days to reduce water fouling while in transit. During transportation it might be necessary to change the water often and even aerate the water. It is also very important to maintain low temperatures during transportation.
When stocking fingerlings into a new pond, it is important to acclimatize the fingerlings first. This is done as follows:
a)    Placing the container with fingerlings into the pond and leaving it for about 15-20 minutes.
b)    Then allowing the pond water slowly into the container and allowing the young fish to swim out slowly

Tilapia Nutrition and Feeding:

There are three types of food used in aquaculture:
1.      Natural food occurs naturally in fish ponds. This includes detritus, bacteria, plankton, worms, insects, snails, aquatic plants and fish. Their occurrence and abundance depends on the water quality and in particular fertilization.
2.      Supplementary feeds usually consist of feed materials available locally such as terrestrial plants or agricultural by-products like wheat bran.
Many kinds of feed materials may be used as supplementary feeds for your fish such as:

• Terrestrial plants: grasses, leaves (e.g. cassava)and seeds of leguminous shrubs and trees/vegetables;
• Aquatic plants: water hyacinth, water lettuce, duckweed;
• Small terrestrial animals: earthworms, termites, snails;
• Aquatic animals: trash fish;
• Rice: broken, bran, hulls;
• Wheat: middling, bran;
• Maize: gluten feed, gluten meal;
• Oil/cakes after extraction of oil from seeds of mustard, coconut, groundnut, cotton, sunflower, soybean;
• Cottonseeds;
• Brewers wastes and yeast;
• Slaughterhouse wastes: offal, blood, rumen contents;
• Manure: chicken droppings, pig manure

Supplementary feeds are available in two forms

i).      Dry feedstuffs such as cereals and cakes with about 10% moisture. These are easier to transport, store, and to distribute to the fish.

ii).    Wet feedstuffs such as waste blood, rumen contents, molasses and brewery wastes with 30 to 50% moisture. Moist feeds do not keep well, and only small quantities should be prepared at a time. These feeds require special treatment, for example mixing with dry feedstuffs to absorb part of the moisture or drying to improve storage life before feeding.
3.      Complete feeds: Are made from selected ingredients to provide all the nutrients necessary for the fish to grow. Under intensive systems, feed provided to the fish must meet all their dietary requirements. The fish rely wholly on exogenous feeds. The feeds must be complete in terms of nutrients supply.
It is important to note that:
i).            Small fish need more food than larger ones.
ii).          Where there is plenty of natural food, less supplementary feed should be used
iii).         Where low stocking densities are used, less supplementary feeds are used
iv).       The better the quality of the feed (low FCR), the less the quantity needed to feed the fish
v).         More food is required in warm water than in cooler water.
vi).       It is therefore recommended for producers to constantly adjust the feeding throughout the production cycle for better results.
vii).      FCR will be affected by Overfeeding, poor feeds, poor pond fertilisation for semi intensive production and poor fish health.
How to feed:
For most fish, feeding twice a day is sufficient - at about 10 am and 4 pm. Earlier than 10 am in the morning, the water is a bit cold and oxygen levels are low so this is not a good time to feed the fish.
If you feed at close to the same time and at the same place in the pond every day, the fish will learn to come for the feed.
Recommended feeding rates for tilapia or tilapia/clarias in Polyculture:

Approx month after stocking	Assumed size of fish	Amount of wheat bran per day	Pelletted diet(26% protein)
1-2	5-20g	1 g/fish	1 g/fish
2-3	20-50g	1-3 g/fish	1-2 g/fish
3-5	50-100g	3 g/fish	2 g/fish
5-8	100-200g	4 g/fish	3 g/fish

Fertilizer and Manure Application:

Where the natural pond productivity is enhanced through fertilizer application, reasonable production can be achieved without exogenous feeding. Although yields will be lower than those obtained with exogenous feeding, fertilizer application will reduce the quantity and expense of feeding. Application of an inorganic fertilizer high in phosphorus should be done prior to stocking fish to create an algal bloom. Tilapia productivity is stimulated mainly by an increase in phosphorus and to a lesser extent by an increase in nitrogen. The inorganic fertilizers used in Kenya are DAP and CAN.
Di Ammonium Phosphate (DAP), Mono Ammonium Phosphate (MAP) and Urea are the cheaper sources of nutrients.

• For Phosphorus; DAP or TSP
• For Nitrogen; UREA

a) Methods of applying chemical fertilizers:
Dissolve the fertilizer in a bucket of water by stirring, and then sprinkle the solution at different points of the pond. If you throw the fertilizer in while dry, it will sink and some of the nutrients, especially phosphorus will be absorbed by the mud.
Application Rates for chemical fertilizers recommended in Kenya:
D.A.P: 2g/m² every week i.e. 200g per 100m² per week.
UREA: 3g/m²/week i.e. 300g/100m²/week.

Animal manure is widely used in Kenya in fish production in earthen ponds. The quality of manure as a fertilizer varies depending on the source animal and the quality of feed fed to the animal. Pig, chicken and duck manures increase fish production more than cow and sheep manure.
Accumulations of manure on the pond bottom produce low oxygen conditions (during decomposition) in the sediment resulting to reduced microbial activity and sometimes result in the sudden release of toxic chemicals into the water.
b) Methods and rates of applying manure

• Crib method: A compost crib constructed using wooden sticks at one or more sides of the pond. It helps fertilize the water gradually. The manure in the crib requires frequent turning to facilitate the release of nutrients.

• Bag method: A bag is filled with manure and tied to the corner of the pond. The bag is shaken weekly or daily to release nutrients.

Manure application rates depend on the size of the pond, which is expressed as surface area of the water in the pond. The recommended rate is 50g of dry matter per m² per week i.e. 5Kg/100m²/week.
The maximum rate depends on the quality of the manure, the oxygen supply in the pond and water temperature. If early morning DO is very low (fish tend to breathe through the water surface) or the water temperatures are less than 18°C, manure application should be discontinued.
At low temperatures the rate of decomposition decreases and manure may accumulate on the pond bottom. A subsequent increase in temperature could then result in oxygen depletion.

c) Agricultural lime.

• Used to improve soil quality, which helps the organic and chemical fertilizers to work better. It also helps to clear up muddy water.
• In red soils; about 20kg per 100m² can be applied. Black cotton soils may require a little more.

Some characteristics of organic and chemical fertilizers:

Organic (Farm manure)	Chemical: - DAP, Urea, MAP, TSP
Contains trace minerals and vitamins.	Contains only what the label says
Uses oxygen to decompose.	Does not use oxygen when dissolving
Is highly variable in composition depending on feeds given to the animals and bedding used	Varies little in composition from what is indicated on the label.
Can help reduce turbidity due to clay silt in the ponds	Does not reduce turbidity
Can help reduce seepage in ponds	Does not act on seepage
Some of the ingredients can be consumed directly by the fish	Not directly consumed by the fish

Harvesting:

Fish produced for consumption should be harvested when they reach market size. In Kenya, tilapia are ready for harvesting within six to nine months depending on the size at stocking, target harvest size, water temperature and level of management employed. The time of harvesting is determined through regular sampling which should be done monthly.
A day or two before harvesting, feeding and fertilizer application should be stopped.
During harvesting:

• Fish should be checked for off flavours
• Fish should be harvested during cool weather (early morning or late evening)
• Harvesting and transportation equipment should be set up well in advance to ensure reduced stress and minimal fish mortality.

Tilapias are best harvested by seining for partial harvesting and complete drainage for complete harvesting.
Pond harvesting can be partial which involves removal of part of the fish stocked from a fish pond and the rest allowed to continue growing. Complete harvesting involves removal of all the fish stocked from the pond.
Equipment required in harvesting fish include, seine nets, scoop nets, clean plastic buckets and baskets, clean source of water and clean fish storage containers.
Once harvested, fish should be handled with care and transported to the market while still fresh.
Where the fish are not destined for immediate sale, simple processing at the farm level can greatly reduce post harvest losses.
Simple processing would include:
i).       Gutting and scaling
ii).      Sun drying
iii).    Smoking
iv).     Salting
v).      Frying
vi).     Deep freezing
It is important to note that the type of processing will be determined by market preferences.

Diseases, Parasites and Predators Management and Control

Occurrence of disease and parasites in farmed fish is mainly as a result of poor husbandry. Disease causing organisms are always in the environment fish live in and they cause few problems. The pathogens naturally exist in a stable “equilibrium” with their hosts until this balance is disturbed through environmental changes and anthropogenic activities.
Fish are normally stressed through inadequate dietary or environmental conditions. The water quality parameters such as pH, temperature, dissolved oxygen may lead to outbreak of disease pathogens and parasites.

Fish stressors:
Some fish stressors that lead to diseases that need to be avoided are;

• Poor handling of fish is a major cause of both bacterial and parasitic infections.

• Translocation of fingerlings/fry from one place to another without proper care can spread diseases and parasites.

• Increased nutrient levels due to intensive cage culture promote proliferation of parasites.

• Pollution due to high levels of ammonia predisposes fish to succumb to large numbers of parasites. Human faeces may be a source of gut parasites especially to common carp.

• Damages of fish by predators lead to secondary bacterial or fungi infections. The predators especially birds and mammals play an important role in life cycles of certain parasites.

Disease, parasites or pathogens may enter fish through gills, penetration of egg membrane, ingestion, rupture of skin, wounds or through the digestive tract.
Note that ; Tilapias are more resistant to viral, bacterial and parasitic diseases than other commonly cultured fishes. Few diseases and mortalities have been reported in semi intensive tilapia farms in Kenya. This could due to low stocking densities in these systems. Lymphocystis, columnaris, whirling disease, and hemorrhagic septicemia may cause high mortality, but these problems occur most frequently at water temperatures below 11⁰ C. The most important cause of mortalities is anoxia ( lack of oxygen) resulting from blooms of algae. Sudden lowering of temperatures to below tolerance levels, which can happen during the rainy seasons, can lead to problems including mortalities.
Main causes of disease in farmed fish
When fish are not fed with the right food in the right way, nutritional diseases occur.
Some of the main causes of disease are:

• Poor feeds and feeding;

• Poor quality or contaminated feed,
• Exposure to extreme conditions or toxic environments;
• Extremes in pH where the water is either too acidic or alkaline
• Presence of toxic gases such as ammonia
• Lack of dissolved oxygen
• Overcrowding and/or behavioural stresses, for example in storage or transport
• Improper and/or excessive handling
• Toxins in food such as fungal toxins in stored feeds ,pesticide residues etc
• Water pollution by agricultural or industrial effluents, sewage effluents, heavy silt loads.

Since prevention is better than cure, it is very important to:
i).       Ensure quality and sufficient water supply, with adequate dissolved oxygen and free of pollution.
ii).      Maintain clean pond environment by controlling silting, plants and proper phytoplankton and zooplankton balance. Regular pond disinfection is recommended.
iii).    Keep the fish in stress free conditions by controlling stocking density, keeping different sizes separate to reduce fighting, providing proper food supply, handling the fish properly etc
iv).     Prevent the entry of disease organisms by:
v).      Preventing entry of wild fish by using screens and eradication them from canals and ponds
vi).     Ensure that all fish got from outside to the farm are clean without parasites or diseases
vii).   Always using good quality feeds
viii).  Regular monitoring of the water entering the farm to ensure of its quality
ix).    Prevent the spread of disease within the farm by:
x).      Controlling predators, particularly birds and mammals
xi).    Disinfect ponds regularly to kill both the disease organisms and their intermediate hosts
xii).   Avoiding water sharing among ponds
xiii).  In case of disease outbreak, remove sick and
xiv).  Bury diseased fish with quicklime away from the ponds; carefully treat infected ponds and disinfect all e dead fish from the ponds immediately
xv).   Always disinfect pond and fish handling equipment
Common disease symptoms in fish
Behavioural signs:

• Decreased feeding
• Weak, lazy or erratic swimming
• Floating on water belly up
• Roughing against hard surfaces
• Crowding/gathering at the inlet

Physical signs:

• Gaping mouth
• Open sores, lesions, loss of scales, bloated belly
• Pale, eroded, swollen, bloody or brownish gills
• Abnormally folded or eroded fins
• Cloudy or distended eyes
• Presence of disease organisms on skin, gills, fins

Fish diseases can either be:
(i)                 Bacterial - which causes diseases like fin rot and tail rot

(ii)               Fungal infections - wooly or cottony patches on the surface of fish, and gill rot causing asphyxia.

(iii)              Parasitic

• Ectoparasites- Those that occur outside the fish body for example those that cause Black spot, white spot, fish louse and Nematode.
• Endoparasites - Those that get into the body of the fish like the Contraceacum, and the Ligula intestinalis.

(iv)            Dietary - High carbohydrate levels in trout feeds, lack of proteins and lipids will result to liver tumour.
Some common fish diseases and their prevention

Pathogen	Symptom	Prevention
Fungus	Cottony grey-white or brown patches on the skin	Proper fish handling Avoid handling fish in cold water. Low organic matter in water
Trematodes	Black spots Yellowish cysts on gills	Control snails and control predators like birds. Remove infected fish.
Bacteria	Loss of appetite. Fin and tail rot. Pale gills Fluid in abdomen	Improved water quality
Nematode (Contracaecum)	Round worm in spiral shape near gills	Not really a problem for fish health but leads to consumer dissatisfaction
Parasitic protozoan	Fish try to scrap their bodies on hard surfaces (flashing)	Salt, potassium Permanganate or formalin bath. Keep water temperature near optimum range for that species of fish.

Nutritional Diseases:

Cause	Symptom	Prevention
1. Lack of proteins	-Poor growth. -Caudal fin erosion. -Loss of appetite.	-Feed protein rich food e.g. soya beans, slaughterhouse by-products, fish meal.
2. Lack of lipids	-Poor growth	-Feed with energy-rich foods

The following should be followed in treatment of infected ponds.
Ponds with infections should be drained and badly infected fish culled.

• Dry the pond under the sun for about seven days
• Dampen the pond bottom
• Spread Lime (Calcium carbonate) evenly over entire surface of pond bottom at the rate of 1500 kg/Ha.
• Wait for 15 days then restock the pond with healthy stocks.

Some common chemicals for use in fish farming
Limes and agro-industrial by-products e.g. rice bran and molasses: Pests control in drained ponds
Organic poisons such as rotenone can control pests in filled ponds
Household bleach is a good disinfectant of non-metallic equipment and working areas.

Chlorine bleach liquid and powder can be used as a strong disinfectant for fish handling equipment
Common salt is cheap and easily available. Kills several disease organisms and have positive effects on the fish by stimulating appetite and increasing mucus secretion, improving resistance to handling.
Formalin is toxic to fish particularly in soft water because it lowers dissolved oxygen levels, make sure treatment water is well oxygenated.
Some common fish predators and their control measures:

Predator	Type of fish eaten	Control measure
Insects and insect larvae	Juvenile fish and eggs and fish just hatched.	i).       Oil emulsion to prevent aerial breathing. ii).      Use of fish that feed on insect larvae especially those that have gills and can remain in the bottom.
Frogs and toads	juveniles of tilapia and catfish	i).       Fence with frog proof wire mesh. ii).      Clear bush around pond. Screen both in and outlets. iii).    Use traps. Adult catfish and bass eat frogs.
Fish	all types of fish	i).       Use screen in the inlets and outlets. ii).      Do pond draining periodically
Snakes	destroy larval and juvenile fish	i).         Clear bush around the pond and fence properly.
Crocodiles, alligators and large lizards.	All types of fish	i).       Proper fencing and keeping dense bushes cut down.
Turtles	prey on catfish	Fencing around pond with wire mesh, trapping.
Birds: Wading birds e.g., Herons and egrets Diving birds. Kingfisher, fish eagle cormorants, pelicans	All types of fish and at all stages especially in shallow waters. Cormorants feed on fish just after the fish are fed- when they are most concentrated.	i).       Proper fencing all round and then above with netting material or manila ropes/strings on poles with bright coloured cloth or metal crossed over the pond. ii).      cover ponds with nets or wire mesh, use flash guns, windmills that revolves and flash brilliantly and bells to scare the birds a way. iii).    The birds can also be actively discouraged by destroying their nests
Otters	Prey on large fish at night killing more than they can eat. They burrow and live under the roots of trees near the water. Otters are very clever They can even open latches on gates.	i).       Proper fencing around the ponds. ii).      The otters can also be trapped using special otter traps set in their passages. iii).    Guard by use of trained dogs. iv).     Fence the pond half way across giving allowance for fish to pass through but not he otter thus providing hiding places for fish.
Man (theft)	All types of fish. This is also considered among the major predators through which fish are lost.	Extremely difficult to control and is most common in cage culture and other intensive fish farming. Can however be controlled by i).         Employing security personnel ii).        Use of trained dogs iii).      Hidden obstruction to prevent pond seining. iv).       Fence the farm and lock securely. v).        Burglar alarms or electrified fence

• If the situation is bad, then trapping or shooting can be used as the last resort in cases of birds and otters but in consultation with the relevant authorities for example the Kenya Wildlife Authority

• Be very careful when poisoning predators, humans and non target animals can be affected.

Record Keeping:

One of the main drawbacks on the economic operation of aquaculture investment in Kenya is a lack of deliberately kept economic records of production operations. Investors who operate without records are likely to make wrong decisions due to lack of information of what is happening in their farms.
The best sources of information needed to advice on proper running of aquaculture investments are properly designed and kept farm records.

What is record?
Record is information that has been systematically and carefully collected and appropriately stored for intended use. To be able to run any business successfully, carefully thought out, properly collected and kept records are a must. For the purpose of keeping track and decision making in any business, comprehensive and well kept records must be kept.
Just as in any other enterprise, properly collected and kept records are important in fish farming enterprises.

The records will:

• Be used in Determining profitability of various techniques of production or systems
• Be used to compare the efficiency of use of inputs, such as land, labour and capital, with that of alternative production activities
• Help the investor in improving the efficiency of farm’s operations
• Be used to preserve institutional memory of the enterprise for future reference.

Good records will, for example;

• Be useful in projection of expected production
• Be useful in determining the amount of inputs requirements for specific ponds at various stages of production
• Be useful determine the expected harvesting time
• Determine the financial health of the enterprise

Some important aquaculture records parameters include:

• Capital investment costs e.g. cost of constructing ponds, hatchery etc.
• Total area under culture
• Individual pond identity
• Individual pond treatments
• Stocking densities and time of stocking
• Species stocked
• Kinds, quantities and cost of inputs used
• Pond productions in amounts and values
• Other productions and values
• Daily occurrences

Classification of aquaculture records
Aquaculture records can be classified into:

• Daily records kept for input usage like feeds, fertilisers, labour and daily occurrence
• Occasional record which are kept for events that do not happen on daily basis. Such records would include:

• Specific pond production (Quantity and values) by species
• Costs of acquisition of inputs
• Cost incurred in new constructions or repairs
• Salaries (both in cash and in kind)

Level of record keeping
How much and how comprehensive kept records are, is dependent on:

• Level of investment; Complex investments require complex records
• Motivation of investor; Serious investors will have more comprehensive records
• Level of aquaculture management: Intensive operations will have more complex records as compared to semi intensive operations
• Skills of the investor (Or manager); Well trained managers will keep better records

As the management levels rises, culture systems become more complex and so is the record keeping. This is the reason the farmer must think very carefully of what he needs to record.
Examples of aquaculture records:

• Fish farming biological management records
• Financial management records include:

Ø     Purchase of inputs
Ø     Sales records
Ø     Salary records
Ø     Inventory of equipment
Ø     Records on payment of rents and hire of equipment, machinery, services etc

• Occurrence book

It is very important for individual farmers to clearly know what they need recorded and the intended use of this. This will assist them in preparing the most effective way of capturing the needed information.
Some examples of simple aquaculture records would include (but not limited to) the following:

Please note that all produce that is lost through spoilage, being undesirable to the market etc, should be captured in the records

Other records to consider include:

• Salary / wages records
• Farm inventory records
• Records on payment of rents and hire of equipment, machinery, services etc
• Pond sampling records

Economic Analysis

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