Fish pond farming is one of the most viable ways to enter South Africa’s aquaculture industry. This method of fish farming is often considered relatively straightforward compared to other forms of aquaculture, and it can be a good option for beginners.
However, success in any aquaculture venture depends on various factors. One such important factor is pond management, which is crucial to the survival of the fish, especially in fighting off diseases.
Marvellous Makhado, a Limpopo fish farmer, shared some key considerations when it comes to pond management.
Take your pick
According to Makhado, there are a variety of pond types.
Conventional ponds are bodies of water that are completely or partially enclosed. These include perennial and seasonal, nursery, raising, and stocking ponds.
The viability of manmade ponds in areas with water shortages is, naturally, very limited. Under these circumstances, rainfed ponds are encouraged, but they may take a longer time to develop and form than ponds fed by other water sources.
Whichever pond system you choose, Makhado said strict management practices must be followed. This is because, contrary to popular belief, fish are highly sensitive animals. Environmental changes, no matter how minor, can trigger periods of stress and illness.
Thorough pond management, Makhado added, should take several factors and processes into consideration.
“From the fish species present, culture activities such as stocking structure and density, fertilisation, feeding, harvesting, and selling, must all be documented,” he explained.
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Things you should monitor
The colour of a fish pond reveals a lot about the basic production processes being followed, as well as potential fish diseases lurking around.
According to Makhado, there are a few ways in which fish farmers can instantly know that their fish are not doing well.
“If they’re sick, you will see they will change their swimming patterns. If they are sick, they start to float and swim backwards. Often their chest will be facing upwards and sometimes it will be laying on the side,” Makhado said.
To stay ahead of potential risks and the occurrence of diseases, fish farmers are advised to regularly monitor the following:
Water depth
Water depth is a critical factor in pond management as it directly affects the overall health of the aquatic environment and the success of aquaculture operations.
“Measuring the water area is necessary to determine the size of the pond for optimal fish stocking and production procedures,” Makhado said.
Water depth is also important because it plays a regulating water temperature and deeper water allows for a larger volume of water, which can hold more dissolved oxygen.
To assess your pond water depth, you can use a 4-5m long bamboo pole with a 25cm diameter wooden disc at the base.
Soft sediment depth
The pond bottom normally contains a soft sediment layer. This layer’s depth can be measured using a 6-8m long bamboo pole with a 10cm diameter wooden disc at its base.
Soft sediments can influence water quality in ponds and impact nutrient levels.
Solid sediment depth
In addition to the soft sediment layer, older ponds contain a solid sediment layer with a low water content.
A 6-8m long bamboo pole with a pointed end can be used to measure layer thickness. The total thickness of the soft and solid sediment layers is proportional to the age of the fishpond.
The sediment layer can sometimes measure more than 2 meters.
LISTEN: Podcast: How to stay one step ahead of fish diseases
Watch out for these diseases
There are hundreds of bacterial, parasitic, and fungal infections that can impact the health of your fish.
Diseases to look out for in pond systems include:
Saprolganiosis: The symptoms include brown flakes growing on the body, similar to white cotton wool.
Treatment: Small ponds can be submerged in a 1:1000 potassium solution of 3% ordinary salt solution or copper sulphate solution for 1-5 minutes in a 1:1000 potassium solution for 5-10 m water.
Larynesis (anchor worm disease): The symptoms include bleeding vascularity, weakness, and patches on the body.
Treatment: Due to a minor illness infection, use bromos 50 in the pond.
Ulcers: It can be found on fish’s belly, head, and tail. Eventually, the fish dies.
Treatment: 600kg of lime per hectare was effectively treated. Cephex at one litre per hectare is also effective.
Bankiomycosis: You will see diseased fish try to consume air from the upper surface due to decaying slits, resulting in asphyxia. The mouth expands and shuts repeatedly.
Treatment: Pollution prevention includes adding new water to the pond, using 50-100kg of lime, bathing in a 3-5% salt solution, and using copper sulphate.
Ulcer or wound: The symptoms are wounds on the head, body, and tail.
Treatment: Use potash in the pond at the rate of 5mg, lime 600kg (3 times at 7-day intervals), cephase solution in 1 litre of water and put it in the pond.
Dropsy (ascites): The symptoms include water in the internal organs and abdomen.
Treatment: Proper arrangement of clean water and food for the fish, and lime at a rate of 100kg per hectare after 15 days (2-3 times).
Understand your fish system
Adequate nutrition is another important factor in fish pond systems. According to Makhado, sticking to feeding schedules is of utmost importance.
“If you feed them at 06:00 every day, it needs to stay 06:00 because fish get grumpy and can lose their temper. If they are used to being fed at 06:00 and then you change it to 09:00, they won’t be happy.”
Makhado emphasised the importance of understanding and maintaining the fish pond systems as it is critical to good fish health management.
Taking the required proactive measures will minimise stress on farmed fish, prevent disease introduction, limit outbreaks to afflicted areas, and minimise losses, he said.
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