Fish Stocking

Stocking fish is an important element of fishery management. Some of the many benefits fish stocking can bring to a fishery are increasing anglers catches and new species. While the United Kingdom has many high quality fish farms and fish supply businesses, fish stocking can be one of the biggest risks for a fish farm and it is essential that before stocking your lake you understand the risks and endeavour to reduce them.

There are several reasons why you may want to stock fish, such as:

  • You would like to change the mix of species or even add a new fish species to the  water
  • You are building a new fishery
  • You want to change the type of fishery you have, perhaps from a specimen fishery to a match water
  • You want to increase the amount of fish that can be caught by anglers

The risks of stocking new fish

By understanding the risks associated with stocking new fish you will be better placed to prevent any problems occurring with your fishery.

The primary risks associated with stocking new fish include:

  • Damage to the ecology of the water due to the sudden increase in fish quantity.
  • Introducing parasites and new types of disease
  • The new fish failing to establish themselves successfully in your water

Protecting your fishery

There are several steps one can take when stocking a fishery that will help to reduce any potential issues. It is important that you do not take any short cuts in this process. Well managed stocking of a fishery can add great value whereas poor stocking methods can bring long term damage.

Question: Do you really need to stock?

It may seem that stocking new fish is the best way to increase angler’s catches, but this may not always be the best option in the long run. While stocking brings an immediate benefit it could be that developing a better spawning habitat will, in the long term, improve fish stocks and catches.

Stocking fish into a fishery

It is important that there is enough space for your new fish to live in order for them to be able to thrive. One way to check if you have enough space to allow for the introduction of new fish stocks is by monitoring how well your original fish stocks are growing. You might find that if you are already overstocked then by simply removing some of the existing fish will give those remaining more space and food, improving both spawning and ultimately angler’s catches.

Question: What does successful stocking do?

Before increasing fish stocks ensure that you know what you want to achieve from doing so, and that you have a way of measuring when you have achieved it. For example, if your intention was to introduce a new species to your water then by monitoring how well they grow will be how you will know if you have achieved your objective. Or, if you introduced fish stocks to improve angler’s catches then by monitoring anglers catch information and match records you will be able to see when you have achieved your aim.

Adding  new fish species

Stocking is often used when adding a new species to a fishery. Expanding the mix of different fish species is often a wise plan, but it is important to ensure that the new species you plan on stocking will not cause any damage to fish that are already native to the water. Some fish do not compete well with other species – for example crucian carp and tench do not compete well against common carp. Every fish species has specific needs and water type and quality is prime among those needs. Ensuring that the water is suitable for the fish to thrive will safeguard a successful stocking. Before adding a new species investigate why it doesn’t already exist in the water you wish to stock.  It’s possible that nobody had ever tried to introduce them to the water before, or that they did but they did not thrive well in the water conditions. Knowing this in advance could save precious time, money and resources.

Stocking consent

Always ensure that the Environment Agency gives you consent to stock new fish – it is a legal requirement to do so. Obtaining consent from the Environment Agency reduces the risk of harming your existing stock with new fish that might have diseases. The Environment Agency will assess the method you plan to use to introduce any new species so as to ensure no damage is caused to the fishery. If you plan on stocking a non-native species of fish such as wels catfish or grass carp then you will need to also obtain a license from Defra.

Health checks

Defra insists that all stocking consents are supported by a certified health check if your fishery is one that is in the floodplain or one where water can flow between two or more bodies of water. Fully enclosed stillwaters do not normally require a health check; however Defra would recommend that you always undertake a health check regardless of the type of water. Agencies such as Defra and the Environment Agency will be able to offer advice on what a health check should entail. Health checks fish farms will have additional analysis to check for the most severe fish diseases. While no health check can categorically guarantee that fish stocks are free from harmful parasites and it is considered to be the best method of protection when stocking fish.

Ornamental fish

While ornamental fish, such as ghost carp, koi carp or goldfish, can add novelty value to a fishery agencies such as Defra strongly recommend that you should avoid stocking these varieties, and certainly do not obtain these types of fish from residential households that no longer want to keep them in their garden ponds.. This is because some of these ornamental species have suffered terribly from disease in recent years and also the disease controls for this type of fish are far far lower than those placed on fish that are grown just for stocking purposes.

Good stocking

A good fish supplier will offer the best advice about the optimum time in which to stock your chosen type of fish. A reputable fish supplier will should offer coarse fish for sale only in the cooler months of the year (between October and March). Stocking and moving fish can be very stressful for varieties of coarse fish, which can lead to susceptibility to various diseases. Because of this it is best to move and stock these types of fish in late autumn or early winter when fish are less active and the oxygen levels in the water are high. Large numbers of fish should not be added at the same, instead introducing fish stocks in small numbers and gradually over a period of time will ensure that the ecology of the water remains stable, thus preventing habitat and water quality issues.

Successful stocking

Stocking is an important element of fisheries management and, when done well, it can reap many rewards. It is not common for disease issues to occur after a new stocking but each year a handful of fisheries will find that they are affected by such issues. However by heeding the advice offered freely by the likes of Defra and the Environment Agency you should ensure that your fishery is not one of the handfuls affected. Proper planning, and a well-executed stocking over a period of time, as opposed to stocking a large quantity in one fell swoop, will help to ensure that your fish thrive over time.

We can supply fish stock and advice on fish stock management and work with domestic and commercial clients in Norfolk, Suffolk, Essex, Kent, London and throughout the United Kingdom. For more information and advice about stocking fish, fish stock management, fisheries management or maintenance and fishery and consultancy services, please email, call 0800 3891990.