|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.|
|Breeds||Sail fish ,striped marlin, blue marlin, black marlin, broadbill, swordfish, shark, tuna, trevally, game fish, amber jack, trout, tilapia|
|Brooding||Fish breeding is a challenge that attracts many aquarists. While some species reproduce freely in community tanks, most require special conditions, known as spawning triggers before they will breed. The majority of fish lay eggs, known as spawning, and the juvenile fish that emerge are very small and need tiny live food or substitutes to survive. A fair number of popular aquarium fish are live bearers which produce a small number of relatively large offspring. These usually take ground flake food straight away.|
|Fingerlings supply||The fingerlings mature in 3 months and are born monthly. This is excellent for the small scale farmer because every month you can have fingerlings for sale. Be sure to watch out for mosquitoes. You will need a labourer to continually feed the fingerlings.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
|Feeds and feeding||Feed quality: The feed should contain all the nutrients required by the fish, in the right proportions for good performance (growth and health). The specific nutrient requirements for fish vary with the fish’s size and reproductive state. The nutrients within the feed should also be easily accessible to the fish and be digestible.Selecting the feed: When selecting a feed, bear in mind the following:The species of fish being cultured. Different species have different nutritional requirements.
The age and size of the fish. Juvenile fish require higher protein in their feed. For grow-out production, a feed with a protein level of 32% is adequate
The quality of Feed being used.
Estimating the Correct Amount to Feed: In order to avoid over or under feeding the fish, the right amount of feed must be given each time. The amount of feed to be provided to the fish per day, the feeding rate (ration), is dependent on the fish’s body weight. Fish adjust their food consumption rates to meet their metabolic energy requirements. Therefore, the required ration varies with time during the production cycle depending on: the fish size (i.e. its average weight) and the pond water quality – notably in terms of water temperature, dissolved oxygen and pollutant levels.
The amount of feed required per ration can be estimated with the help of a feeding chart and calculated as: average fish size (weight) x feed rate (%) x total number of fish in the pond.
|Environmental requirements||Optimal Temperature: Various species and strains of tilapia differ in tolerance to low temperatures, but growth is poor at water temperatures below 16OC and death occurs from temperatures below 12OC. Most will not feed or grow at water temperatures below 15oC and will not spawn below 20OC. The normal water temperature should be between 20 to 30oC. Higher temperatures will result to fish death.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.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.
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.
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.
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.
|Husbandry||Fish is reared at a rate of 2 fish per metre squared. In Kenya two to three crops of fish can be produced annually depending on the water temperatures. Cold temperature reduces harvests. The fish are fed on a ratio of 60g/m2/day. However the feeding depends on the size of the fish.|
|Pest & Diseases||Pest Name||Symptoms||Control|
|Fungus||Cottony grey-white or brown patches on the skin||Proper fishing handling. Low organic matter in water|
|Bacteria||Black spots and yellowish cysts on gills||Improved water quality|
|Trematodes||Fluid in abdomen||Control snails and predators like birds|
|Fish Nematodes (Contracaem)||Round worm in spiral shape near gills||Not really a problem for fish health but leads to consumer dissatisfaction|
|Equipments||Seine nets, scoop nets, clean plastic buckets and baskets, clean source of water|
|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 flavors
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.
|Regions||Central and western provinces|
|Expected yields||An acre of ponds produces 4000 fish. With a minimum of two harvest per year, the annual yield is 8000 fish.|
|Processing||Processing involves Gutting and scaling, Sun drying, Smoking, Salting, Frying and Deep freezing|
|Place||Fish are Locally marketed for subsistence consumption and exported whole.|
|Price||Price of a Fish is Kshs. 200 per piece and about Kshs 400 per kg.|
|Products / Uses||Fish and Fish mealProcessed fish products include; fish oil fish emulsion fish glue kelp|
|Nutritional value – per 100 g / % Daily Values||Total fat 0.7g, saturated fat 0.1g, polysaturated fat 0.3g, monosaturated 0.1g, cholesterol 41mg 13%, sodium 31mg 1%, potassium 392mg 1%, protein 19g 38%, vitamin A 1%, calcium 1%, vitamin B12 16%, iron 4%, vitamin B6 20% and magnesium 7%|
FACTS & FIGURES
|Fishes were the first animals to evolve backbones. The ray-finned fishes are the largest group of fish.Some species of fish migrate between freshwater and marine environments to spawn.Fishes move by creating a wave motion that moves the length of its body. Fishes are cold-blooded (ectothermic) animals.
Many species of cichlids brood their eggs in their mouth.
There are only two groups of jawless fishes alive today.
The lateral line system on some fish detects variations in water pressure.
|1 acre fish ponds:Income: 8000 Fish * Kshs 200 = Kshs. 1,600,000Expense: Fish meal Kshs. 20 * 100kgs*300days = Kshs. 600,000
Miscellaneous expenses are: Kshs. 200,000
Net: Kshs. 800,000