In an attempt to understand the vibrancy of the aquaculture industry, and indeed the reasons why starting a fish farming small business is a viable idea, it is necessary to delve into statistics.
Sample the following statistics obtained from FAO’s 2016 State of World Fisheries and Aquaculture Report:
- In 2014, for the first time ever, more farmed fish than wild-caught fish was consumed by the world’s population.
- In 2014, fishery exports from developing countries were valued at US$80 billion
- World aquaculture production continues to grow and currently provides half of the fish consumed by the human population
There’s clearly a lot going on for the aquaculture industry now and the future outlook is by all means positive.
If you can access a suitable piece of land that is in proximity to a reliable water source you can definitely consider starting your own freshwater aquaculture small business.
This is what you must know:
1. You’ll need to select the type of fish production system you will apply
In general, the form of aquaculture you will be doing will fall under one of the following categories:
- Extensive fish farming — Operations that utilize natural water sources and natural food sources i.e. those that are already available in the water. Low investment costs are required
- Intensive fish farming — Here more sophisticated management techniques are applied to optimize fish production. The investment cost and operational costs are higher. Fish can be produced all-year-round and in high quantities per unit of area.
You can choose either of these two forms of aquaculture in implementing the fish production system of your choice.
The suitability of these production systems is generally determined by the source of water available to you.
A cage culture production system will be feasible if you have access to a lake or pond.
A smooth bottomed pond will be feasible if your water source is a well, reservoir or creek.
A brief description of these fish production systems:
- Cage culture — Here you will have floating cages in which you will stock fingerlings and then feed them a nutritionally complete diet. The startup cost is low and the system works well on a small scale. You however need to use a lake/pond that is bigger than one surface acre and only slightly deep. Plant cover shouldn’t exceed ⅓ of the lake/pond.
- Pond culture — Here you will stock fish in specially designed ponds that contain standing water. This is generally the most economic means of fish production and virtually every species of fish for aquaculture can be grown using this system
- Continuous flow systems — These describe raceways, ponds or tanks through which new water is constantly flowing. Raceways are generally made of concrete while tanks are typically made from concrete or fiberglass. In many situations these systems have been shown to be uneconomical.
- Recirculating system — This refers to indoor tank systems where water is filtered and reused.
Based on its clear advantages, fish pond culture is the most popular system.
This guide will focus on fish pond culture as the basis of starting your fish farming small business.
2. You’ll have to find an appropriate site where to start your fish farm
Selecting an appropriate site for your fish farm small business is the most important stage in this type of project.
The following are the most important characteristics you ought to look out for in as far as site selection is concerned:
Availability of the water — It will be important for you to consider the variations in types of water flow that may characterize the inland water system you plan on using.
These variations include:
- Perennial system — surface water is available all year and it does not drain during the dry season
- Seasonal system — flow occurs during the annual rainy season; can be dry for several months
- Episodical — flow is periodic or intermittent, tends to flow during one prolonged period but is not seasonal or predictable
- Transitory — the flow (generally supplied by precipitation) is brief and infrequent when it happens, and is then followed by a dry spell
Considering all the above types of systems, only a perennial system can be relied on to sustain your fish farm all year round. The constant water supply will ensure that the pond water is regularly renewed thereby facilitating favorable oxygenation and maintaining suitable water levels.
The amount of water available for your fish farm will in turn depend on your pond’s size, the type of soil at the site, and the climatic conditions of the area.
Water volume — The volume of water required can be calculated by measuring your pond’s volume using the formula:
Volume = Length X Width X Depth
Water loss — This can occur through:
- A leak in the drain
- Evaporation — Here the amount of water lost will depend on wind, humidity and sunshine i.e. the area’s climate
- Infiltration — The water can be lost through seeping into the soil i.e. infiltration
Stream flow — To ensure that your fish farm will be in business throughout the year you will need to ensure that adequate water supply and volume is sustained.
This means that you must have access to a water source that will replace the volumes of water lost through the three ways that have been described above.
To maintain sufficient water levels on a one-hectare fish farm a flow of 2 to 5 liters per second will be required. You must therefore ensure that this will still be the case during the dry season.
On the other hand, you must ensure that your fish farm will not be in a flood-prone area such as near a slope bottom. In the event of a flood it is quite possible that all your fish will be lost.
How to measure flow:
For low flows you simply need to measure the time it takes to fill a bucket of known capacity. You will time this using a stopwatch.
For stronger flows you will need to do a series of calculations as explained by the diagram below:
- First, measure the area of the wet cross section S in m² using the formula: S = l X p
- Secondly, with a stopwatch, measure the speed (V) of a half-floating object moving from A to B in a regular part of the stream: V = AB/t
- Thirdly, calculate flow (D) using the formula: D = V X S
Quality of the water — While having enough water is definitely important, ensuring that this water is of the right quality, in terms of its physical and chemical characteristics will be crucially vital in determining whether or not your fish farm small business will be established.
You will therefore need to have the water analyzed in order to ascertain the following:
Physical parameters — temperature, density, viscosity, color, turbidity, transparency
Chemical parameters — pH, conductivity, alkalinity, hardness, dissolved oxygen, phosphorous, nitrogen ammonia, nitrites, nitrates, carbon dioxide
It is preferable that chemical analysis be done during the dry season as the various components of the water will be more concentrated thanks to evaporation.
Temperature — Fish are unable to control their body temperature and as such they have a minimum and maximum lethal temperature limit. It will therefore be important to determine the annual average water temperature in your region and then identify species of fish that can thrive in that range of temperature
Dissolved oxygen — The amount of dissolved oxygen and percentage saturation in the water can be measured using a digital probe. This amount of dissolved oxygen will depend on:
- Water temperature
- The pond’s altitude (height above sea level)
- The amount of salts dissolved in the water (oxygen will be highest where there are no dissolved salts)
pH — Fish generally prefer water that is neither too acidic nor too alkaline. The ideal range of pH is therefore 6–8.
Note that the pond’s pH can change quickly.
For example, rainwater carrying acids from the soil in the area can enter the pond and lower its pH. In this case you’ll need to restore the pH to neutral by adding limestone to the water.
Nitrogenous compounds (waste products) — The accumulation of ammonia in the pond will be as a result of decomposing materials i.e. plants and dead fish, and the waste excreted by fish. In a system with relatively neutral pH ammonia is first converted to nitrite (NO- 2) and then nitrate (NO- 3).
High levels of nitrite will reduce the oxygen-carrying ability of the fish’s blood and cause their gills to change color from red to brown. You’ll need to replace the water or transfer the fish to correct this situation.
Nitrate is generally non-toxic at low levels. A sudden increase of nitrate, however, will result in a sudden growth of plants and algae in the pond thereby depleting oxygen levels during the night.
Interestingly, an attempt to reduce the nitrate levels may result in the plants death, further lowering the levels of dissolved oxygen.
Phosphorous — This is necessary for the survival of pond organisms and often important for algal growth regulation and the pond’s food webs.
Nevertheless, even before you have the water’s chemical parameters analyzed you can personally confirm whether or not the water has:
- a bad smell
- a bad taste
- an unpleasant color
- very much turbidity i.e. too many suspended particles (muddy water)
You can measure the water’s transparency (a function of the amount of natural food or suspended particles in the water) using a Secchi disk.
You should also check for the proximity of factories because some effluent from these establishments can contaminate the water and thereby render it unsuitable for fish farming.
The type of soil at the site of your proposed fish farm should have the physical characteristics that will assure permeability and the stability of the pond’s dikes. It should also have the right chemical characteristics that will assure the water’s productivity.
Soil texture describes the relative proportions of sand, mud, or clay particles of different sizes, in a given soil.
Finding out what the texture of the soil at the site is like will give you an idea of its permeability, and how easily the construction work will be done. Simple tests can be used to investigate texture as follows:
- Use some soil to make a ball in your hand and then throw the ball up and catch it. If the ball crumbles you’ll confirm that the soil contains too much sand; if it remains compact this will confirm that it contains enough clay
- Use some soil to make a ball and then throw this ball at a vertical wall some 3 meters away. If the ball adheres to the wall you’ll confirm that it’s suitable for pond construction
- The most conclusive test (as described in the illustration below) will involve digging a waist-high hole in the morning and then filling it up with water. In the evening some of the water will have seeped into the ground. You will fill the hole up once more and then cover it up with boards or branches. If the hole still has most of this water in the morning you will confirm that the soil is ideal for pond construction.
The area’s topography
Your proposed fish farm should be located on a site with favorable topography and which will therefore facilitate the following:
- Pond construction, pond number, and pond surface size
- The supply (and draining) of pond water by gravity
- Construction of dikes without too much soil displacement
- A favorable slope. This should be between 1% and 3% i.e. the horizontal to length ratio should be 3 cm to 100 cm. The slope should therefore neither be too steep (resulting in to fast a runoff) nor too shallow (requiring the construction of a dam to store the water). The absence of a slope will result in zero water flow i.e. the pond won’t drain
If you are in a hilly area you can construct runoff ponds; levee-type ponds will work best if you have flat land.
3. How to go about fish ponds design — introducing barrage ponds and diversion ponds
A fish pond can be defined as a shallow body of water that is used for the controlled farming of fish, and that is adapted to facilitate easy and complete drainage.
The following are the main components of a fish pond:
- A plate — this forms the pond’s bottom
- Dikes — These surround the pond and form walls within which water is contained. These walls must be impermeable and must have the ability to resist water pressure
- Intake structure — This collects the water required to fill the pond
- The emissary — This is a river or canal that allows for drainage
- Supply canal / Water inlet — This brings collected water to the pond
- Draining canal / Evacuation — This allows drainage toward the emissary
- Water inlet device — This regulates the flow of water towards the pond and prevents the water from flooding
- Water outlet device — This will preferably be a monk and it will be used to control water level and pond evacuation
- Outfall / Overflow — This ensures safety by allowing the evacuation of excess water
- Filters (if necessary) are used to prevent animals and particles from entering or exiting the fish pond
Fish ponds can be classified according to their water supply, drainage systems, building materials, and use.
As concerns their use, the following types of ponds exist: spawning ponds, nursery ponds, brood ponds, storage ponds, fattening ponds and integrated ponds.
The focus here is however on fish ponds that you can use to start a fish farming business.
Accordingly, the best ponds will be those that can be completely drained and have all-year-round running water supply.
Two river-fed fish pond types that fit this description, and which you can implement, are barrage ponds and diversion ponds.
Barrage ponds allow all the water coming from the source to pass through them. In constructing them you must be aware of the river’s maximum level and discharge during the rainy season, after a heavy downpour.
If your water source is a small river you will need to block it thereby creating the dam that you will use as your fish pond.
You will then install a monk in front of the dam to drain the pond.
You will also make spillways capable of evacuation even in the worst of floods; their failure to do this may result in the entire dam being swept away.
If your water source is a big river you will be better off building a diversion pond, considering that the river will get much higher during the rainy season.
Note that for the barrage pond system, increasing the number of ponds is impossible. Also, blocking a river in order build these ponds may result in conflict with the people living downstream.
Diversion ponds allow only a portion of the water from the source to pass through them. Both the entry and exit of water are controlled.
Constructing a diversion pond will require you to diverge part of a stream into a supply canal that will then bring water to the pond.
You will typically be required to construct a small deviation dam in front of the supply canal.
This dam will ensure that the supply canal will always have a constant water level. Surplus water will then pass through the dam’s spillway.
- If your water supply is well controlled it will be easier for you to manage your ponds, say, during fertilizing the water and feeding the fish
- If your pond has a regular shape and correct size, its management and adaptation for specific purposes will be easier
- Your water supply and site’s topography will largely determine your choice of pond type
- Diversion ponds whose water supply flows through gravitational force are preferable
The pros and cons of a diversion pond system:
Characteristics of fish pond design
1. General criteria
Depending on the requirements of your fish farming small business you may need to build a series of fish ponds, and which will allow you to get regular monthly harvests all year.
To limit your construction work and costs, and optimize water availability, it is advisable to have your ponds harvest basins aligned with the site’s topography.
The building of terraces will typically result in a larger surface area, and better water retention.
You should also position downstream dikes across the flow of water and in the basin in order to increase the amount of water available for storage at the site.
2. Fish pond shape
If you have an even water surface you should shape your pond in such a way that the overall length of the dam is minimized.
If you have regular ground you will have an easier task constructing a rectangular pond although it’s length must not be too elongated.
3. Adapting the slope
The orientation of your fish ponds will vary depending on the slope’s angle but this should minimize excavation.
If your slope is 0.5 to 1.5% your ponds must be oriented in the direction of the bottom of the slope, following the natural slope.
If your slope is greater than 1.5% the pond must be perpendicular to the slope. In short, the more the slope increases, the smaller your ponds should be.
4. Fish pond layout
Your ponds can be positioned in one of two ways:
Here the fish ponds will depend on each other for water supply, from the upper ponds to the lower ones, and a steeper slope is therefore required.
A key advantage is that you will need fewer draining and supply canals.
However, because the same water is flowing through the ponds, the risk of all ponds becoming contaminated with disease is heightened, and implies that all the production can be lost.
Draining the ponds will also be difficult.
Here your fish ponds will be independent from each other and each will be directly supplied with water by the supply canal.
Each of the fish ponds can be isolated thereby reducing the risk of contamination. Each of the ponds can be independently drained and they all have the same slope.
5. Fish pond size
The size of your fish ponds will be determined by the following considerations:
- Quantity of fish to be produced
- Level of management — extensive ponds are larger than intensive ponds
- Resource availability i.e. the quantities of water, seed fish, fertilizers and/or feed available
- Harvest size and local market demand — you shouldn’t produce too much than your market can consume
6. Fish pond depth
Generally, fish pond depth doesn’t exceed 1.5 meters. The shallowest part should be at least 0.5 meters deep in order to limit the growth of aquatic plants.
4. Construction of a diversion pond for your fish farming small business
Having come up with a suitable design for your fish farm’s ponds the next step will be to construct them.
It’s important to note that fish pond construction should be completed during the dry season.
The following steps will be necessary if you are to construct a high-quality diversion fish pond:
1. Planning of the fish ponds layout
To facilitate the study of the site with the aim of identifying the best possible locations for the fish ponds it will be necessary for you to partially clear the ground using machetes.
You will then proceed to survey the site; your aim should be to identify the line of steepest slope — this is what will allow you to build fish ponds that will enjoy the best possible drainage and water sanitation.
2. Clearing the site proper
After you have marked the boundaries and visualized the site, you will now proceed to clear the area. You will need to ensure that all the outer corners of the fish ponds’ surface area can be well determined. This will require you to mark the boundaries using posts, rope or wooden stakes.
After you have marked this area you should mark an additional area extending beyond the dikes, and which will serve as the passage and working area around your site.
Clearing should involve the following actions:
- Clearing the zone by removing all vegetation (plus roots and stumps to avoid future pond seepage) and all large stones
- Clearing the passage and working area
- Clearing all trees and shrubs in the area extending 10m around the dikes and working area, as well as the area around the access roads, water supply and drainage facilities
- You should thoroughly clean the area including removing termite mounds and animal burrows and then filling up the resulting holes with clay
3. Installing the water supply i.e. water intake and canals
Your fish ponds water supply will be comprised of a water intake, the main supply canal, and small canals that will bring water from the main canal to the fish ponds.
Your water intake should include the following elements:
- A diversion structure that will regulate the water level. It should be high enough to supply the water intake without flooding
- A device that will regulate the level of entry (and flow) inside the structure and that will be used to regulate the water supply to the fish ponds and generally assist in transporting water
- A structure to protect the entry way and prevent debris from entering into and damaging the water intake. Stilts can do the job.
You will need to ensure that the source’s water level will always be sufficient thus allowing water to be drawn from a desired depth, and reducing the likelihood that the water intake will be flooded.
In designing the supply canal you must ensure that it will have a very weak slope and be capable of supplying water all through the year.
Note that you should dig a canal dry — not as water is seeping in as this will result in too steep a slope at the canal’s bottom.
4. Drainage canals
Bearing in mind that your fish ponds should be built in such a way that they can be completely drained any time of the year, it follows that the bottom of the drainage canal should be lower than the bottom of the fish pond.
It will be quite risky for you to use the bottom of the valley as your drainage canal because during a flood the water level in the valley may be higher than that in the fish pond’s bottom.
If on the other hand the water level at the bottom of the valley is permanently lower than that of the fish pond’s bottom then you can use it as a drainage canal.
5. Staking out the fish pond
You can now proceed to mark the boundaries of the fish ponds on the land bordered by the drainage and supply canals using stakes.
These stakes will represent the location of the dikes and also act as a guide for the excavation work.
You will need four rows of stakes for the main dike, three rows for the upstream dike, and two for the side dikes, with the stakes being spaced two meters apart in each row. The dimensions of your dikes will determine the spacing between the rows of stakes.
6. Dike construction
Seeing as the dikes will need to be watertight to ensure that the fish ponds can retain water, your site should be thoroughly cleared as has been explained earlier.
You will need three types of dikes as follows:
- The upstream dike, parallel to the supply canal
- Lateral dikes, perpendicular to the upstream dike and main dike
- The main dike which will be downstream and whose embankment will support the greatest water pressure in the fish pond. This will be the thickest and highest dike.
Each of your dikes will have the following components:
- Foundation or base
- Bench, berm or top
- Banks (embankments)
Each of your dikes must be:
- capable of resisting water pressure equal to the water volume retained in the fish pond
- high enough to prevent water from flowing over
Once you have completed dike construction you can now start constructing the fish pond’s base.
7. Construction of the fish pond bottom
To ensure that your fish pond can be completely drained you will need to have its base on a soft slope that is inclined toward the outlet.
The base’s construction is done by smoothing its bottom while remaining slightly above the projected dimensions.
If yours is a small fish pond you can have its slope in the range of 0.5 to 1.0%, from inlet to outlet.
If it’s a larger fish pond (> than 400 square meters) you would be better off installing shallow drainage ditches with a slope of 0.2% around the drain rather than creating a single slope across the entire pond bottom.
You can have these drainage ditches arranged in a radiating pattern or in a fish-bone pattern.
8. Fish pond inlet structures
You will need the following inlet structures to control the amount of water flowing into the fish pond:
- Pipe inlets
- Open gutter inlets
- Canal inlets
For all inlet structures ensures that you:
- place them at the shallow end of the pond
- have the bottom of the inlet at the same level as the bottom of the water supply canal, and preferably at least 10cm. above your fish pond’s highest water level
- have them horizontal (with very little if any slope)
- have them arranged in such a way that the water will splash and thereby get well mixed up upon entering the pond
- construct them in a manner that will prevent the entry of undesirable aquatic animals or fish into your fish pond
To limit fish pond erosion you should place blocks of stones under your water inlets. These stones must be tough enough to resist erosion themselves.
You should also place filtering devices on the inlets in order to help improve the quality of incoming water and limit the entry of wild fish into your pond.
9. Fish pond drains
You should make plans for installing draining devices before the construction of dikes begins.
Drains will help you to:
- Keep the level of water in the fish pond at optimal level
- Completely drain the pond, and harvest fish, when necessary. In this regard, the drains should ensure that your fish pond can be drained in a reasonable amount of time
Drains typically have three main components:
- A collecting area inside the fish pond. This is where water drains from and where fish are collected for harvesting
- A water regulation device that includes drain plugs, valves, control boards, screens and gates
- A device for draining water out of the fish pond e.g. a pipe, or an opening cut into the pond wall, etc.
During fish pond drainage the water flow should be consistent; this will ensure that the fish won’t be excessively disturbed.
Additionally, your drains should be such that:
- There won’t be loss of fish during drainage
- Water can be drained from the top, bottom and intermediate levels of the pond
- Surplus water can be drained off
- They can be easily cleaned and serviced
- Their construction and maintenance costs are relatively low
There are several types of fish pond outlets.
Nevertheless, for small ponds (3 to 5 ares) you can use a simple pipe made of iron, concrete, PVC, wood, etc.
This can be an up-stand pipe that you can swivel down to drain the water.
You will need to cover the pipe’s opening with a screen to prevent fish from escaping as you drain the pond.
For larger ponds (>100m²) the use of a monk is most advisable.
The monk drain
A monk is a drainage conduit that forms a ‘U’ near the pond’s interior, and is extended at its base by a drain that’s used to evacuate the water. The monk’s structure consists of:
- A vertical three-sided tower (i.e. the monk) typically built to be as high as the dike
- A pipeline running through the dike and sealed to the tower’s back at its base
- A foundation for the tower and pipeline
- Grooves for the wooden boards and screens that form the monk’s fourth side
10. Filling up your fish pond and testing the water
As soon as the fish pond is complete you should fill it up so as to:
- Confirm that all the structures (water supply, canals, inlets and outlets) are functioning properly
- Confirm that the dikes are strong and impervious
- Speed up the stabilization of the dikes
The preferred process for filling the fish pond up and testing it is as follows:
- Filling the pond very slowly to a maximum depth of 0.4 meters at the outlet
- Shutting off the water supply and retaining the water in the pond for a few days. This is the time to carefully check your dikes, repair crevices and collapsed sections, and also confirm that the earth is well compacted
- Draining the pond completely and leaving the pond dry for some days. You should check the dikes again and make any necessary repairs
- Filling the pond again, very slowly, to a maximum level of about 0.4 meters higher than the first level
- Shutting off the water, checking the dikes, and then after a few days completely draining the pond
- Repeating the filling/drying process until you reach the pond’s maximum level
- Checking and repairing dikes as necessary
5. Selecting fish species for your fish farming small business
In selecting the species of fish that you’ll grow on your fish farm you can go for local species that are popular in your region.
You may also decide to start culturing exotic fish species for which there is market demand.
There are a number of reasons why culturing exotic fish may make sense for you:
- Some exotic fish grow better and faster than local varieties
- Some exotic fish are preferred over local fish with regards to consumption
- Crossing an exotic fish with a local one may result in offspring that grows better and tastes better than either parent — this is termed as ‘hybrid vigor’
In choosing the exotic species of fish that you will culture on your fish farm you will need to consider two main factors:
- You will need to identify a species that can thrive within the water-quality and temperature that your region offers
- You need to identify a species for which fingerling supply won’t be a problem. If this happens you may be required to build a hatchery, a facility that requires high technical expertise in addition to being cost-intensive
2. Biology of the species
- Growth rate — you’ll need to identify species that can grow quickly and therefore reach market size in a shorter time. Note that it may be more cost-effective to culture higher-valued species as opposed to cheap, fast-growing varieties
- Feeding habits — the species you choose should have dietary requirements that can be met by both the pond and yourself
- Reproductive biology — it’s recommended to choose species that breed easily and reproduce many young
- Hardiness — your species of choice must be able to adapt well to being cultured
- Market — there must be sufficient market demand for the species you want to culture
- Profitability — all the costs that you incur in production i.e. pond maintenance, purchasing fingerlings and feeding them, etc, must be sufficiently offset by your revenues and thus earn you a good profit
Starting with a tested variety of fish that has good demand in your area is quite advisable. Upon finding commercial success with this species you can make a decision to expand your operations.
To maximize the yield of your fish farming small business you can do polyculture i.e. the growing of two or more fish breeds in the same pond.
You also need to ensure that you purchase your fingerlings from a reliable source, say, the local fisheries department or a reputable farmer.
Fingerlings should be introduced into the fish pond as soon as possible but you need to do this gently so that they won’t suffer shock and die.
The following are some species that you can consider for your fish small business:
1. Sharptooth catfish (Clarias gariepinus)
For this species you’ll need to provide feed that contains 35–42% crude protein. You can culture this species semi-intensively or intensively. High fish density may however make it difficult to achieve good water quality control. Also, the need for size sorting will require high management input.
It’s possible for you to achieve an output of 40–100 tons/ha.
2. Common carp (Cyprinus carpio)
This is the world’s most commonly cultured aquaculture species. It is easy to breed and grow, and it grows fast. It also has good disease resistance.
There are other varieties of carp e.g. silver carp, bighead carp, grass carp, black carp, mud carp, etc.
3. Tilapia (Oreochromis niloticus)
Fondly referred to as ‘aquatic chicken’, tilapia is widely and successfully cultured across the world. The species is characterized by fast growth rate, breeding ease, good taste, and hardiness.
4. Rainbow trout (Oncorhynchus mykiss)
This is a very popular and high-value food fish. It is fast growing and has good market demand where it earns good prices. It is however not tolerant to low oxygen or high temperatures, and it’s also susceptible to disease.
5. Ornamental fish
There are numerous species of these including goldfish, cichlids and koi.
Unlike the previous species that are bred for food, ornamental fish are bred and sold live for the aquarium trade whose marketing is well established.
Growing ornamental fish requires relatively sophisticated infrastructure but a lower volume of water is needed. Breeding them on a small scale can be viable.
6. Feeding your fish
While your fish will mostly eat the small animals and plants that grow in green water, it may be the case that this food source is not of the desired quality, leading to slow growth of the fish.
In such a situation you may be required to provide supplementary food.
In doing so you must realize that different fish species have different requirements in terms of nutrition and diet.
You must also realize that small fish need more food, relative to their size, than large fish do, and this because of their greater metabolic rate.
Nevertheless, where natural food is abundant and of high quality, the requirement for supplementary food will be lower.
Being cold-blooded, fish don’t have to use energy to maintain a stable body temperature and they are therefore more efficient at food utilization than other animals.
Each species of fish has an optimal range of temperature for growth and within this range the metabolic rate and need for food increases as the optimal temperature is attained. It follows that fish in warmer water need less food than those in cooler water.
As has been previously observed, different fish have different nutritional and dietary requirements.
For example, carnivorous fish will need a higher protein diet than herbivorous species.
Accordingly, you should know the feeding habit of your species of fish as follows:
- Herbivores — these feed only on plants e.g. grass carp and Tilapia rendalli
- Carnivores — these only feed on other animals or meat e.g. trout and bass
- Omnivores — these feed on both animals and plants e.g. common carp
- Planktivores — these feed on very small plants and animals in water e.g. mullet and silver carp
- Detritivores — these feed on dead plants or animal material on the bottom e.g. Oreochromis mossambicus
Various supplementary foods that you can feed to fish:
- Terrestrial plants
- Aquatic plants
- Small terrestrial animals
- Rice (broken, polishing, bran, hulls, etc.)
- Wheat (middlings, bran, etc.)
- Maize (gluten feed, gluten meal)
- Oil/cakes left after oil extraction
- Sugar cane (molasses, filter-press cake, bagasses)
- Coffee pulp
- Brewery wastes and yeast
- Kitchen wastes
- Slaughterhouse wastes
- Silkworm pupae
- Manure e.g. chicken droppings and pig manure
If you decide to use commercial fish feed you should realize that its cost will be about 50% of the total cost of producing your fish. You should as such do all you can to prevent wastage.
Commercial fish pellets are available in floating and sinking pellet varieties.
Floating pellets will allow you to observe the fish feeding thus giving you information about their size and condition. You’ll also get to see how much food your fish can eat in a single feeding.
Sinking pellets are intended for fish that prefer feeding at the bottom and species that don’t rise to the water’s surface to eat floating pellets.
As expected, it will be difficult for you to know whether or not the fish have eaten to their fill, and there is therefore the likelihood of overfeeding the pond, and which will result in its pollution.
How to feed fish
You should feed your fish at the same time and place every day. This will allow you to easily monitor fish stocks.
You should stop feeding the fish when they stop eating.
If your pond is small in size you can do the feeding by hand but if it’s much larger you can use a flat-bottomed boat to supply the feed around the pond.
The buildup of waste at the bottom is to a large extent dependent on the amount of artificial feed provided.
The accumulation of this waste will lead to increased levels of ammonia and nitrate, which will then lead to decreased oxygen levels. As such, if you note that the fish aren’t feeding you should remove the uneaten or excess food from the pond.
There are several reasons why fish may stop feeding. As soon as you observe this happening you should immediately address the problem. The reasons include:
- Poor quality feed
- Low oxygen
- Change in pressure
Adequate measures should be taken to ensure that food storage is done properly thereby preventing excessive loss or quality deterioration. You should ensure that:
- Both the air and food are kept as dry as possible
- Air and food temperature are kept as low as possible
- Storage facility temperatures and moisture levels are well managed to avoid creating a conducive environment for mold (fungi) and insects which may contaminate the food
- Rodents and birds should be prevented from accessing food and consuming it
- Losses due to human activity, e.g. theft and indirect damage, should be prevented
7. Fish pond care, maintenance and management
The care and maintenance of your fish pond will be an integral part of the effort to make yours a successful fish farming small business.
The main aim of fish pond management is to ensure that your fish will live in an environment that is conducive for their growth and thriving.
You should carry out the following maintenance activities in between harvests:
- Draining and drying the pond
- Turning the soil
- Disinfection and liming
Between harvest cycles you should allow the bottom of your fish pond to dry out for 2–4 weeks. However this period can be reduced to a few days to preempt the formation of cracks in the dikes and on the pond’s bottom when the clay shrinks.
In this interval time bacteria will break down the soil. Drying will also kill any pathogens, parasites and undesirable filamentous algae.
You should also clear away any weeds and plants that have not been eaten by the fish. This will help to reduce the number of breeding areas for snails and mosquitoes which transmit bilharzia and malaria respectively.
When this is done you should plough the soil, and depending on its health, you can add compost and chemicals such as lime.
The compost will provide the nutrients that will be needed by the algae and plants in the upcoming breeding cycle.
The lime will:
- Condition the soil and make it suitable for rearing fish
- Correct the soil’s pH (it should therefore be applied properly)
- Prevent the build-up of chemicals that are harmful to the fish
- Speed up breakdown of compost and fish waste
- Reduce the chance of fish disease, especially gill-rot
- Help to eliminate pests like leeches
Fertilizing the pond will ensure that phytoplankton productivity will be sustained. Algae will turn the pond’s water green thereby making it difficult for predators to see and catch fish.
You should therefore ensure that adequate amounts of nitrogen, phosphorous, carbon, potassium and calcium are contained in the fertilizer that you’ll apply, whether this is of the organic or inorganic variety.
Organic fertilizers — You can obtain this fertilizer from the dung of cows, pigs, goats and sheep, as well as the droppings of poultry and ducks. Alternatively, you can use farmyard manure, sewage, green manures, compost, etc.
Cow dung is however the most widely used manure for non-drainable pond culture systems.
Inorganic fertilizers — These have the ability to quickly dissolve in water and their use will therefore quickly avail nutrients to the pond.
Nitrogenous fertilizers contain nitrogen as the main element. Most of these fertilizers make pond soil acidic and it is therefore prudent to choose a fertilizer based on the type of soil in your pond.
Nitrogenous fertilizers are essential for newly constructed ponds that are poor in nitrogen and whose bottoms don’t have sufficient organic matter.
It’s best to maintain the phosphorous to nitrogen ratio at 1:4.
Phosphatic fertilizers are the best fertilizers for fish culture, considering that virtually all ponds don’t have enough phosphorous. The superphosphate varieties are the most soluble in water, with single superphosphate being readily available and the most widely used.
These fertilizers are slowly released over a number of years depending on the nature of a pond’s bottom.
As you are drying your pond, the following maintenance tasks should be carried out:
- Clearing the pond’s bottom — Generally, mud will tend to accumulate in the deepest part of the pond (in front of the monk). You should remove this mud so that during the next harvest the water will be as clean as possible for the fish. This mud is however very rich in nutrients. To avoid wasting it you can spread some of it across the pond’s bottom and then use the rest as fertilizer in your garden.
- Drain repair — It is likely that the drains will be filled in the course of production. To resolve the filling problem you should dig a passage that will follow the trail of the initial passage. The mud removed should be thrown far away from the now-clear drains.
- Dike repair — Your task here will be to restore the pond’s original slope which will have been degraded during production. Slope restoration can be done by banking up the dikes with new clay. You’ll also have to fill up any burrows that may have been dug into the dikes by small animals.
- Water inlet repair — This will be necessary if your water inlet was too short at installation resulting in water eroding part of the dike. Further erosion can be prevented by placing a large flat rock or a pile of rocks at the bottom where the water jet falls. The stone(s) will break the jet thus reducing its eroding power. Alternatively you can repair the dike wall with a stone facing.
- Monk maintenance — You should check the external rough coats of monks made of brick or masonry. The coats should be remade if they have slightly deteriorated. Also check to see if the joints of the cement have already been attacked. If so, rejoin the stones or bricks and then re-plaster the unit. You should also replace defective small boards.
8. Harvesting your fish
Harvesting fish from your pond will depend on two considerations:
- If your fish pond can be drained — You will harvest the fish by draining the pond into the catch basin and then using a scoop net to collect the fish
- If your fish pond can’t be drained — You’ll need to drain out as much water as possible and then use seine nets to catch the fish. Note that this technique won’t be as effective as totally draining the pond
Steps in harvesting fish from your ponds:
- Assemble your equipment
- Set up holding tanks for your catch
- Seine net your pond and sort your catch
- Clear the catching basin of sludge as the water level drops
- Catch remaining fish from the basin
- After purging in the holding tanks, pack your catch into drums
In addition to seine nets you can also use the following catch equipment:
- Gill net — you can use this for selective harvesting of large fish
- Cast net — this is good for catching large fish without damaging them
- Dip net — this is used to handle and transfer small quantities of fish
- Handlines and hooks
After harvesting the fish you should immediately cut them open along their underside and pull out their guts. You should then wash the fish with clean water and place them in cooler boxes.
The fish should then be marketed immediately, preferably in a local market to ensure that they are sold fresh. Sorting the fish by size, i.e. small, medium and large, will allow you to maximize your revenues.
9. Tips for the success of your fish farming small business
- Identify your business opportunities and markets beforehand
- Ensure that your fish farm is properly sited and that you have adopted appropriate production technology
- Tailor your production to meet market requirements profitably and reliably
- Make your investments in a step-by-step manner. It is prudent to start small and then build up in case you are making profits
- Seek advice from sources with a proven track record
- Learn from your mistakes and those of other fish farmers
- Keep records and use them
- Follow the recommended best management practices
- Use the best feed locally available to you correctly
- Always be involved in the running and/or management of your fish farming small business
- Always check for new market opportunities and if your resources can allow it, make an investment in your fish farm
- Sell your fish immediately and appreciate the turnover
- Honor all the promises you’ve made to your customers; this will occasionally mean making a no-profit sale or replacing fish at zero charge
- Analyze your farm’s data and use it to assess production and economic performance
- Use your own data as the primary basis for making management and investment decisions