MANAGEMENT IN FISH CULTURE

CHAPTER TEN

MANAGEMENT IN FISH CULTURE

Culture management involves all practices or activities carried out in fish culture facilities aimed at ensuring a healthy environment to increase fish yield.

10.1                         POND MANAGEMENT PRACTICES

1.     LIMING: Liming is applied by broadcasting the lime across the water bodies. It may be applied to kill predators and parasites. It also prevents water loss. Liming materials are quicklime, calcium hydroxide, calcium carbonate, calcium silicate, wood ash, gypsum and calcium bicarbonate.

Functions of lime in a fish pond

-It encourage the growth of plankton.      

-The productivity of the pond is improved by liming.

-It prevent water loss in the pond.

-It help prevent wide swing in P^H.

-To correct the acidity in the pond.

- It aid the effect of fertilizer.

-It help organic matter breakdown.

-It add calcium and magnesium which are important in aquatic animal physiology.

2.     FERTILIZATION: Application should be done before or after impounding. There are two methods of applying fertilizer to fish pond.

i.      Broadcasting- Fertilizer is spread evenly and directly into pond water or pond bottom. It is labour intensive and workers could be exposed to hazard.

ii.     Sack method-  Fertilizer or manure is put in a sack and the sack is lowered into pond water. Nutrients leach out slowly from fertilizer or manure into pond water. Sack is withdrawn when no longer required.

There are two types of fertilizer

I.     Inorganic fertilizer e.g N.P.K, Phosphoric acid (P₂O₅), potash, superphosphate, calcium nitrate, potassium sulphate.

II.    Organic fertilizer e.g poultry dropping, cow dung, compost manure.

Advantages of fertilizer to fish pond

1.     It provide essential nutrients to the pond

2.     It improves the condition of the pond.

3.     It stimulate growth of natural fish food organism.

Effects of applying quantity of organic manure to fish pond.

1.     It increase bacteria activities.

2.     It increase acidity of the water.

3.     It result to oxygen depletion and mortality of the culture species.

4.     It increase risk of infections

5.     Removing the manure from pond is expensive and labour intensive.

DIFFERENCES BETWEEN ORGANIC FERTILIZER AND INORGANIC FERTILIZER IN A FISH POND.

ORGANIC FERTILIZER	INORGANIC FERTILIZER
1. Natural.	Artificial.
2. More mineral nutrient is available.	Specific nutrient is available.
3. Large quantity is needed to fertilize a pond.	Small quantity is needed to fertilize a pond.
4. Cheap to produce.	Economical expensive to produce.
5. Locally produce from animals waste.	Industrially produced.
6. Slow in term of reaction time in the pond.	Fast in term of reaction time in the pond.
7. Smelly and application can be messy.	Easy to apply.

 

3.     STOCKING: The right type and right number of fish is placed in a pond at the right time ( cool hour of the day). The type of aquaculture influences the type of fish stocked. Transportation of fingerlings should be done by using oxygenated bags or clean big containers.

Factors that depends on the number of fish to stock in fish pond.

-          Size of pond.        -Experience of producer.        -Length of growing season

-          Market size desired.         Water supply.

4.  DISEASE CONTROL: Keep pond well aerated to prevent disease outbreak. Foot baths should be provided for visitors at the entrance of the farm. Farm equipments or tools are kept clean and disinfected. Minimized stress or handling fish. Fish stock are quarantined. Keep the environment clean and maintain good water quality.

5.  MONITORING: Water quality is checked daily to ensure that water quality maintain at optimum level. Daily observation of fish for unusual behavior. Always check sources of pollution within the pond eg overfeeding or overstocking or excess fertilization. Make sure the pond water is flush when necessary.

6.  FEEDING: Feed is introduced in pond water by broadcasting, point placement or automation. Fish could be fed two or three times a day, at a specific time.

7.  HARVESTING: Regular harvesting of fish should be done to prevent over population. Outbreak of diseases etc. Harvesting should be done after six months of stocking either period or total harvesting.

 

10.2                         CAGE CULTURE  MANAGEMENT

Today, fresh water cage culture is practiced as alternative type of agriculture for small and limited-resource farmers. It allows farmer to use existing water resources that may or may not used for other purpose. The fish produced are usually sold to local markets. The most popular cage culture species are tilapia, catfish, carp Heterotics etc

STOCKING IN CAGE CULTURE:- Stocking rates in cages depend on the species and the carrying capacity of the water body. Tilapia can be stocked in cage at the rate of 20-40 fingerlings per m³ while not lower 4 or 5 catfish per cubic foot.

FEEDING IN CAGE CUTURE:- The fish in cages should be fed with formulated feed with a good protein content. General, floating feeds are preferable in order to prevent wastage and pollution of the water. Mouldy feed should be discarded.

DURATION OF CULTURE:- Culture periods depends mainly on water quality, the type of species and quality of feed. For tilapia and catfish the culture period is between 6 and10 months.

WATER QUALITY MONITORING IN CAGE CULTURE;

        Dissolved oxygen level is the most important water quality parameter to understand when raising fish in cages. If the oxygen levels below about 5mg/l can reduce feeding and growth of fish dissolve oxygen level below 3mgll can stress fish while level below 2mg/l can result in mortality of caged fish. Oxygen measurements should be recorded weekly or even more often when conditions suggest possible problems.                                                  When dissolved oxygen level drop below 3mg/l stop feeding the fish. If dissolved oxygen level drops below 2mg/l, will be needed to save fish in cage. Do not resume feeding fish until oxygen level recover.

HARVESTING IN CAGE CULTURE :- Total production in cages increase as the stocking rate is increased. However there is a density at which tilapia become too crowed and water quality within the deteriorates to a point that causes a decline in growth rates. In cages, production should be limited to 30-50 kg per m³. Tilapia continues to grow above these levels at gradually decreasing rates, but convert feed poorly and the risk of loss due to oxygen depletion or disease is greater.

TILE 1: STOCKINGS RATE IN CAGE CULTURE

SPECIES	TEMP RANGE(OF)	TEMP EXTREMES (OF)	STOCKING TIME (MATH,TEMP OF)	STOCKING RATE(no/Ft3)
1). Rainbow trout	55-65	<40>70	Sept, nov,60-65	4-12
2).Channel catfish and bluegill	80-85	<45,>95	May- July60-70	5-9
3).Tilapia	80-90	<55>	June-July 70	5-12

ADVANTAGE OF CAGE CULTURE

1.         Resource use flexibility-cage culture can be established In any suitable body of water. Including lakes, pond, mining pits, stream or river with proper water quality access and legal authority.

2.         Low initial investment.

3.         Cages lend themselves to straight forward observation of the fish.

4.         Simplified harvesting.

5.         Multi-use of water resources.

6.         Growth of fish in cage is faster than in ponds.

7.         Easier stock management and monitoring

                                            DISADVANTAGES OF CAGE CULTURE

1.         Cages attract predators like birds, crocodile, mammals etc

2.         Risk of loss from poaching or damage to cage from predators or storms

3.         Less tolerance of fish to poor water quality.

4.         Dependence on nutritionally-complete diets.

5.         Leveling turned over.

        10.3                                         SHELL FISH CULTURE

        Shellfish culture includes various oyster, mussel and clamp species. These bivalves are filter and or deposit feeder.                                                                                                        The first operation in oyster culture is to catch the juveniles (seed). Strings of shells are suspended during the summer spawning season from racks placed in coasted areas such as bays and inlets after setting the seed is hardened a process of draping the string over racks so that they are out of water for a considerable period of time during each tidal cycle.Two methods of hanging oysters culture are usually practiced. In the first method, seed oysters are transplanted to the rafts about 1 month after setting to grow, no hardening is done. These oysters are harvested at the end of one year .This method is characterized by a short growing period and low labour cost. In the second method seed oysters are hardened until autumn or early winter. They are the transferred to the rafts t grow and are not harvested until the following year.

10.4                                                 POLYCULTURE

Polyculture is the practice of culturing more than one species of aquatic organism In the same pond. Polyculture  should combine fish having different feeding habits in proportion that effectively utilize the natural foods.

Different species combination in polyculture system effectively contributes also to improve the pond environment  catfish and tilapia and bass.

SELECTION OF POLY- CULTURABLE SPECIES

The considerations of selecting fish species for polyculture are listed below;

1.         High growth rate of selected fish species in the cultivated environment.

2.         High demanded species in the market.

3.     Selected those species which has high growth rates and low mortality rate in high density.

 4.    The species which don’t caught by disease easily.

5.     Those species should select which has more useable flesh in the in body.

6.     Select those species which are tasty and contain high nutrition.

7.     The fish which are phytoplankton vorous or omnivorous

8.     The fish which grow naturally by consuming less protein.

STOCKING IN POLYCULTURE:- The most common polyculture fishes practice in African is tilapia and catfish. The catfish must be stocked in high densities in order to obtain a complete reduction of the tilapia fingerling, as it preferred to feed on the supplied feed. In general the ponds are stocked with two tilapia per square metre and with I catfish per square metre

FACTORS AFFECTING SPECIES SELECTION AND STOCKING RATES:- 1.Water temperature (2) market value of fish (3) pond fertilization practices (4) feeding habits of fish (5) potential uncontrolled  spawning in grow out ponds.

BENEFITS OF POLYCULTURE PRACTICE

1.         Better and complete utilization of natural feed.

2.         Enhancement of natural food.

3.         Improvement of water quality;- In pond, improvement of oxygenation occurs due to the presence of silver carp or tilapia. Silver carp consumer excess algae which otherwise could create an imbalance between production and consumption of oxygen. Tilapia may also improve oxygenation by consume bottom organic matter that would otherwise have been mineral by oxygen consuming bacteria

4.         Control of undesirable organisms:-  carnivorous fish are used to eliminate shrimps proliferation.   

10.5                                     INTEGRATED FISH FARMING

Integrated fish farming refers to the simultaneous culture of fish or shell fish along with other culture systems it may also be defined as the sequential linkage between two or more culture practices. Fish culture can be integrated with several systems for efficient resource utilization.

       Type of integrated fish farming.

 

Basically the integrated fish farming is two types

a)         Agric-based fish farming e.g. Rice-cum-fish culture Horticulture-cum-fish farming etc

b)         Live stock fish farming e.g. poultry-cum fish farming, Duck-cum-fish culture, pig-cum-fish culture, cattle-cum-fish culture, goat-cum-fish culture etc.

ADVANTAGES OF INTEGRATED FISH FARMING

1.         Efficient waste utilization from different culture practice for fish production.

2.         It reduces the additional cost for supplementary feeding as well as well as   fertilization.

3.         It is an artificial balanced ecosystem where there is no waste.

4.         It provides mores employment avenues.

5.         It reduces the input and increases output and economic efficiency.

6.         The integrated fish farming provide fish along with meat (chicken, duck, beef, pork etc) milk, vegetable fruit, eggs, mushroom etc

The practice has potential to increase the production and socio-economic status of weaker section our society.

 STRUCTURE QUESTIONS

1.            Levee in a pond is the same thing as the (a) bottom (b) inlet (c) water      surface (d) wall (e) outlet

2.            The act of putting fish in a pond for the purpose of rearing is called (a) fishing (b) fixing (c) liming (d) loading (e) stocking

3.            Which of the following is not considered in stocking a pond? (a) age (b) density (c) ratio (d) sex (e) shape

4.            Which of the following is not a problem associated with net, pen and pond aquacultures? (a) use of antibiotic and pesticides (b) disruption of human life in coaster community (c) increased rates disease and parasites relative to wild fish (d) large amount of waste released into the environment

5.            What is a water shed? (a) a small house used for strong water (b) the area of land that drains to a body of water (c) an area just below a body of water where grass grow  all of the above

6.            What is an example of and impervious cover? (a) Concrete (b) graved (c) tree (d) the all of the above.

7.            What materials might line the bottom of a man made wet pond? (a) clay (b) gravel (c) sand (d) flower

8.            Why are areas with physical structures under water very suitable for fishing? (a) hese physical structures are filled with fresh water that helps the fish survive (b) coral reefs provide the chlorine that fish need to survive (c) underwater volcanoes spew magma  that feeds the fish (d) the structures provide shelter and safety for fish.

9.            The suitable soil for fish pond is (a) clay (b) sandy (c) loamy (d) sandy – loamy

10.          The essential features of a standard fish pond include all except (a) dam (b) spill way (c) core trench (d) none of the above

11.          Liming can be done by adding—except (a) N.P.K (b) limestone (c) cow ding  (d) stocking.

12.          Which of the following activities should be carried out on old fish pond? (a) Mapping and liming of water.

13.          The function of the  dyke of a fish pond is to (a) Prevent erosion (b) Facilitates drainage (c) Hold water (d) Facilities impounding.

14.          The bottom of a fish pond should slope towards the (a) Inlet (b) Outlet (c) Embankment (d) Free board.

15.          When is it necessary to lime an earthen pond? When the pond (a) Is leaking (b) Water is muddy (c) Water is acidic (d) Water is alkaline.

16.          The sides of fish ponds are sloped in order to facilitate (a) Drainage of ponds (b) Flooding of ponds (c) Removal of excess water (d) Erosion control.

17.          The act of introducing water into the pond is called (a) Embankment (b) Enrichment (c) Impoundment (d) Inducement.

18.          The act of combining fish rearing with poultry production is called (a) extensive system (b) integrated fish farming (c) semi-intensive system (d) intensive system.

19.          The following are fish management practices except (a) feeding to satisfaction. (b) Fertilization of eggs (c) fish health management. (d) Selection of fish species.

THEORY

1.      Define the term pond management.

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2.      Describe four pond management practices.

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3.      Describe two methods of applying fertilizer to fish pond.

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4.            Enumerate three advantages of organic fertilizer to fish ponds.

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5.      Give three examples of inorganic fertilizer that could be used in a fish pond.

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6.            State three effects of applying quantity of organic manure to fish pond.

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7(a).         State five functions of quicklime in a fish farm.

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(b)            Mention three materials that can be used in place of quicklime in a fish pond.

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