It is a known fact that effective management plays a vital role in the success of aquaculture business both on a large and small-scale level. Effective management can simply be put at proper and timely maintenance of the farm in order to meet up with human needs.

Farm implies all activities carried out on the farm and installations which include successful broodstock manipulation, seed production, stocking, sorting of fish into sizes, disease and pest/ predator control, proper water management, control of human poaching, timely harvesting, marketing and adequate record keeping.

Scientifically, farm management considered the basic economic principles in business management. These are comparative advantage, diminishing returns, substitution, cost analysis, opportunity cost, and enterprise choice and goal trade-off.

However, despite prudent and genuine application of the highlighted principles, an effective, prompt and timely decision has to be taken. All data collected and analysed based on the application of the basic economic principles cannot make decision by themselves, but they have to be harnessed properly by an expert in the field (manager) in making rational decisions.

The decision-maker must be well equipped with good and high level skill of reasoning, an economist, a management specialists as he would have to choose between different alternatives, some of which have uncertain consequences.

Despite all said, personal element, including perceptions to risks involved and personal attitude to consequences, plays a major role in the final decision, even though it is preferable to handling complex decisions by mere intuition.

How much effort and time should be spent on decision analysis would depend on the importance and the decision, time and cost involved in the analysis. In fact, an analysis at the simplest level, consisting of evaluating the various choices available and scrutiny of the consequences of each and the chances of the success, can lead to better management decisions.

1. Site Selection

All meteorological and hydrological information about the area (generally available from a reconnaissance survey), such as range and mean monthly rainfall, evaporation, sunshine ,wind speed and direction, flood, water table, e.t.c., have to be assessed.

In inland aquaculture, the most commonly used installations are earthen pond farms (rearing and nurseries ponds) and hatcheries therefore, soil characteristics, the quality and quantity of available water and the ease of filling and drainage by gravitational pull are very essential.

The nature of site vegetation indicates the soil type and elevation of the water table. Dense vegetation, particularly tall trees make clearing more difficult and expensive while high ground-water level may create problem of poor drainage and inconvenient use of mechanical equipment for pond construction.

2. Pond Construction

The pond is the environment in which fish live and where all activities relating to its life took place (from stocking to cropping), pond may be earthen or tank. If pond is earthen, it could either be drainable or undrainable.

Drainable pond is constructed in a way such that water flows into the pond easily by gravity via inlet pipes from its source and the same pond could be easily emptied also by gravity through outlet pipes buried into the soil. No mechanical energy is needed to carry out either operation and although it may slower but saves cost.

Undrainable pond may have inlet pipes to bring water into the pond, but it is unable to empty pond partly or completely except by a mechanical aid (pumping machine) thereby increasing cost of production. However, a practical experience has equally shown that, the construction and operation of a farm with a pumped water supply system can be more economical than that of a tidal water farm.

Fish tank may be concrete, fibre glass, plastic or wooden and in various sizes and shapes ranging from circular, rectangular to trapezoidal forms for different sizes of fish. It could be sub-surface or made to be completely surface and it is expected that such is protected with locks to prevent human pilfering.

3. Soil Test

Soil analysis of the intending fish pond site is an often over-sighted but very important activity to be undertaken when pond is to be constructed. The quality of soil is important in pond farms, not only because of its influence on productivity and quality of the overlying water, but also
because of its suitability for dyke construction. The ability of the pond to retain the required water level is also greatly affected by the characteristics of the soil.

Such soil tests to be carried out vary from simple visual and tactile inspection to detailed subsurface exploration and laboratory tests. Sandy clay to clayey loam soils are considered suitable for pond construction.

Texture (relative proportion of sand, silt and clay particles) and porosity are the two most important physical properties to be examined. By mere touch and feel, one can determine the texture of a soil sample.

A sample of soil that is kneaded and rolled into a bar and bent to form a ring around the thumb without any cracks must be clayey. If it cannot be made into bar and remains separate with visible grains when dry, the sample is sandy. If the sample does not fall into either of the two categories, then it can be categorised as silt or loam.

4. Water Availability

Availability of good water both in terms of quality and quantity is very essential for successful fish farm operations. The availability in required quantity is particularly important in land based aquaculture systems.

It is therefore prescribed to investigate thoroughly, the extent and seasonality of water sources as well as liability to pollution, which may arise from agricultural run-offs, industrial effluents, sewage disposal and flooding.

Toxic substance in water supplies can affect aquaculture, particularly in hatcheries and therefore, regular sampling of pond water must be done in order to forestall crisis on the farm.

Among water quality parameters of great importance to aquaculture are pH, dissolved oxygen, nitrite-nitrate ratio, temperature and alkalinity.

Ground water from springs, wells, or underground seepage is the best source of water for fish farms. Other sources of water including surface waters, runoff water, and even municipal water can be used to grow fish.

Of course, all sources of water must be free of fish diseases and parasites, nuisance fish, predators, silt, pesticides, chlorine, and other chemicals that are harmful to fish life. A good water supply of sufficient quantity and quality is absolutely essential for all fish farms. Water
quality also restricts the type of fish that can be reared and production rates.

Whichever the source is, the availability of good water supply round the year remains incontestable. In cases where water source is seasonal but very abundant at the peak of the season, it has become the usual practice in certain part of the world to impound water for aquaculture purposes while a water control device called spillway is put in place where farm is susceptible to flooding. Before considering developing a fish farm, have your water shed tested?

5. Pond Preparation

The pond is completely drained of water and the bottom allowed drying till it cracks. Desalting of the pond is done if the pond is very muddy. The pond must be in proper shape and good status if the purpose, aims and objectives of the culturist must be realized.

Therefore the following operations are recommended for execution prior to stocking of pond with fingerlings (baby fish).

6. Drying the Pond Bottom

The pond has to be completely drained of water and the bottom is allowed to dry till it cracks. Desalting of the pond should be carried out if the pond is muddy.

7. Removal of Unwanted Organism and Aquatic Weeds

While drying the pond undesirable organisms e.g. Frogs, mollusks, fish predators and aquatic weeds such as Water hyacinth, Pistia, Lemna weeds e.t.c are removed. After ensuring this, the pond is fenced round and all inlet and outlet pipes are properly screened while surrounding
vegetation is kept low.

Dense aquatic vegetation occurring either along the pond margin or inside the pond must also be controlled. These weeds compete with the phytoplankton for available nutrient in the pond water and hence diminish overall pond productivity.

Unwanted organisms like lizards and other reptiles must be chased out or killed as well as crabs and birds while aquatic macrophytes can be removed manually by hand or cutting, mechanically or biologically using grass eaters or herbivorous fish species e.g. Distochodus spp., Grass carp e.t.c.

8. Repair of Pond Structures

The essence of site survey and farm planning and design is to ensure convenient and effective utilization of pond or farm facilities once they are properly constructed and fitted. However, it may not be out of place to always ensure that adjoining pond structures such as embankments
and monks are checked and repaired if necessary and all cracks and holes sealed before pond is filled up with water.

Similarly, fish screens and water filtering structures if clogged are thoroughly cleaned or replaced, damaged pipes replaced and eroded dykes should be strengthened before stocking of pond with fish This activities on the farm in synonymous with ensuring the safety of the entire business by minimising risk sources.

9. Liming and Fertilization

Liming is done in order to improve conditions for fish production although not in the form of fertilisation but terms of favorable edaphic condition of the pond to bring about increased pond productivity. It also increases soil pH thereby creating room for more available carbon
dioxide for phytoplankton to photosynthesise.

When pH increases water is prevented from being acidic and so pond mud is able to enhance solubility of phosphates. Adequate liming aids flocculation of colloidal particles and soil microbial activities thereby increases the rate of decomposition of organic matter and cycling of nutrients.

Materials commonly used for liming fish pond include calcium oxide (quick lime), calcium hydroxide (hydrated lime), agricultural limestone, basic slag and liquid lime. In the absence of these, wood ashes can also serve the purpose but will require a large quantity in order to achieve the desired performance.

The rate of application of lime in fish pond varies with pH and the amount of clay and organic matter present in it. Agricultural limestone and basic slag are the only liming material that can be applied in large quantity to pond before stocking and even after stocking pond with fish for some make-ups.

Calcium oxide and calcium hydroxide can be toxic to fish and should be applied in small quantity to ponds only before stocking due to their toxic effects. Liming rate range from 200-1000kg/ha of liming material depending on individual potency.

The higher application rate is for material like agricultural limestone while the lower application rates go for material like calcium hydroxide.

The pond is immediately filled with water to a depth of about 0.6m and left for 2-4 days to observe any leakages or seepages. It is later filled up to required depth and fertilized.

Fertilisation is however done in order to make water more productive by aiding the growth of natural fish food organisms (planktons). Inorganic fertilizer e.g. Urea and N.P.K. and organic manures are the basic two types of fertilization materials that could serve the purpose.

10. Stocking

Stocking of pond means releasing into the pond an adequate number of selected fish species to be cultured over a specified period of time, which are of uniform size. Stocking is usually done a week after fertilization. Usually stocking density (number of fish species per unit area) of a pond is dependent on the system of culturing, which may be monoculture or polyculture.

Fish fingerlings for stocking ponds can be produced by the farmer himself or purchased from a reputable hatchery and are transported either early in the morning or in the evening.

During stocking of pond, fish should be lowered carefully into the water and allowed to swim out of the container after acclimation in order not to further stress them.

The pond should be visited the following morning to check for mortality (ies) and if found, should be removed at once and replaced with healthy ones from the same source. Culturable fish species in Nigeria include Clarias gariepinus, Oreochromis niloticus, Heterobranchus bidorsalis, Lates niloticus, Gymnachus niloticus, Chrischthys nigrodigitatus, Heterotis niloticus e.t.c. and many species of shellfish like Oyster and prawn.

There are so many possible reasons for raising fish and also available resources are as well of diverse quality therefore it is important to examine all existing factors before deciding what type or species of fish to be cultured.

Read Also: Evolution and the Study of Fish (Ichtyology)