After constructing the earthen pond, what are the steps you are expected to take before putting the fishes in the water?
The first step to take after constructing the fish pond is to put a mosquito net round the earthen pond, this to prevent the entrance of predators like: frogs, toads, crabs, and snakes etc. into the earthen pond by themselves.
Then apply slaked lime and leave it for 4-7days so as to kill any of the predators that may be in the pod already. After 7days, you can apply fertilizer like poultry droppings, organic or inorganic fertilizer to make the soil fertile for the growth of phytoplanktons.
Leave the fertilizer for 4days after which you introduce water into the pond. Allow the water to settle down after which you can stock the pond by allowing the fingerlings/juveniles to swim out of your basin into the pond.
Common Water Management Systems in Aquaculture
There are at least three kinds of water management system available for catfish farming namely;
- Re-circulatory System
- Flow-through System
- Stagnant-pond System
Re-circulatory system, in catfish production, is made up of close or partially-close system of indoor water management techniques where used water is treated for re-use in catfish farming. Used water is treated for chemical, gaseous, biological and solid waste before re-use.
Water is treated by different techniques and equipments to ensure healthy aquatic environment for catfish production. Also, the system controls pH and water temperature to ensure a conducive environment for fish growth.
Generally, re-circulatory system is made up of fish maintenance tank and composite system. A complete re-circulatory system may comprise the following; Tank, screen/sand filter, filters, aerators/oxygen pumping machine, submerged heater/chillers/heat exchanger, linking pipes.
Merits of Re-circulatory System
- It promotes efficiency of water management by ensuring limited water resource is judiciously used.
- It ensures economy of land because of its high density stocking capability.
- It is environmental-friendly. Used water is treated before being released into the environment.
- Controlled production environment reduce to barest minimum certain infections.
- Encourages mass production of catfish per area of land.
- Increases survival rate and ensures low mortality due to reduced risk of diseases.
- Stable environment for optimal growth.
De-merit of Re-circulatory System
- Expensive to set up.
- High cost of maintenance.
- Can only be handled by trained manpower.
- High cost of operation.
- Breakdown in any part of the system will affect the entire system.
- Cannot be operated in absence of electricity.
Flow- through System is water management system in fish farming in which water is allowed into the pond through an inlet pipe(s) and used water is released into water body to keep the pond refreshed. Sometimes, water coming into the pond may be treated or may not be treated.
The main reason for setting up this system is to limit water pollution and its effects. Where there is no much water, used water from the earthen ponds is re-used by allowing it to settle down in settlement dam/tank. Flow-through system could be intensive, semi-intensive or extensive system.
Pond operating flow-through system is carefully constructed in such a way that fresh water is allowed into the pond either through pipe network or concrete raceway. In earthen ponds, flow-through system can be operated manually by linking the source of water (stream, river, dam, etc.) to a receiving pond from where other ponds get their share of water.
The used water is released through the last pond in the row. However, this might not be feasible in concrete ponds. Most often, source of water to concrete pond is mostly higher than the level of the pond. This will enable water to flow from the source into the pond without any aid of electricity.
Merit of Flow-through System
- Simple to set up.
- Low setup cost.
- Easy to maintain.
- Low cost of maintenance.
- May not need electricity to operate.
- Can be handled by people of little or no training.
Demerit of Flow-through System
- Can only be efficient where water is available in good quantity.
- Where inlet water is not treated, infection can find its way to the pond.
- Not effective in dry season.
- Water can be polluted through the supplying source.
- Pipes can be blocked by unscreened particles.
- It could be at the risk of flood when inflow of water is not controlled during rain.
- Temperature of the pond depends on environment condition.
Pond/Stand-Still System is a static system of water management where pond water is rarely refreshed through external source. It is often used where there is no stable surface water to refresh the pond. However, farmer must be sure of the water retention ability of such an area.
After pond preparation, pond is filled with water either mechanically or naturally recharged through ground water for production of fish for a season. Ponds under this system are under-stocked or moderately stocked to ensure fishes are raised for the whole season without much water management challenges.
At the time of harvest, pond water may be completely drained by the use of pumping machine or lease pipe. Where farmer is not sure of the recharging power of the ground water, pond is poisoned to retain the water for another season production.
Merit of Pond System of Water Management
- Less expensive to maintain.
- Less likely to be affected by external disease/ infection.
- Easy to manage and maintain.
- Less likely to be affected by flood.
- Can be used in absence of surface water.
Demerit of Pond System of Water Management
- Cannot be used for high density production.
- The whole stock can be lost in case of disease outbreak.
- When moderately/overstocked, fishes may not attain their growth potential.
- Large space of land is required for production.
How To Clear Up Green Earthen Pond Water
If you have green pond water, it means that you have a type of algae blooming in there, plus some other substances too. Let’s talk about how to clear up that green pond water right now.
Green pond water is almost always caused by a certain type of algae blooming in the water. There are various ways to help get rid of algae and cut back on that green tinge.
One of the best ways to clear up green algae pond water is by increasing filtration. First of all, you should already have a good 3 stage filter in place, on that engages in all 3 major types of filtration, these being mechanical, biological, and chemical filtration. Mechanical filtration removes waste that can discolor the water, plus it removes waste than breaks down and releases substances into the water.
Biological filtration clears the substances out of the water, like ammonia and nitrates, which are created when waste and organic matter breaks down. Chemical filtration removes other toxins, colors, and odors from the water. This is important because algae feeds on things like ammonia.
Therefore, a good filtration system will help cut down on green water. If your filtration system is not powerful enough, you might need to perform an upgrade, get a new one, or just get a second one. Also, be sure to maintain your filtration system and clean it regularly.
Placing your pond in an area that is not too sunny, at least not all day long, will also help cut down on green water. Algae, just like other plants, needs sunlight to perform photosynthesis. Without as much sunlight, algae will not be able to bloom and therefore your green water problem should clear up.
There are animals you can add to your pond which will eat the algae as soon as it blooms. Koi fish, goldfish, frogs, and snails will all eat algae.
Dye The Water
Yes, we are talking about clearing up green pond water, but we are talking about green water caused by algae. You can in fact dye your pond green, blue, or even purple in color, at least partially (more on Pond Dyes over at this article).
This will help stop sunlight from penetrating too far into the earthen pond, thus taking away one of the food sources which algae needs to bloom.
Add More Plants
The final thing that you can do to help clear up green earthen pond water is to add more plants to the mix. First off, submerged plants will filter out things like ammonia and nitrates out of the water, thus removing the fuel that causes green algae blooms.
Second, you can add some floating surface plants into the pond, as this will help block some sunlight from getting through to the water, thus also removing a food source from the algae.
Folks, the bottom line is that changing earthen pond water on a weekly basis is essential for the health of the community. Yes, it does take some time and effort to do each week, but it is absolutely crucial, and there are some methods that are easier than others. If you have green earthen pond water, follow the above tips to remove it.