Pond Fish Care Guide

Ponds are popular garden features in the UK and are often filled with various species of fish including goldfish, koi, sturgeon, orfe, rudd and tench.
All of these species (except sturgeon) are members of the Cyprinidae family and can be widely found throughout Asia and Europe.
Due to their popularity,the majority are captive bred.

Biology

Tench, Orfe and Koi can grow up to 75cm in length and therefore benefit from being kept in a larger pond.
Koi are perhaps the most famous pond fish with multiple colour varieties available, however, they are slightly more delicate than other species and require good water quality with minimal fluctuations.
There are different colours of Orfe and they should be kept in groups of four or five otherwise they are likely to become stressed.
Tench can be found in different colours (dark green and gold) and associate with the bottom of the pond.

Sturgeon will grow very large, with adults reaching 200cm, however 100cm is more likely in a garden pond.
They can be kept singly, but will require a large pond and cool, highly oxygenated water.

Goldfish remain smaller making them appropriate for most pond systems.
The most common maximum body length is up to 30cm. There are several popular colour varieties including Shubunkins, Sarasa, and Red Comets.
Rudd also remain smaller than the other species, unlikely to grow over 40cm, and will benefit from being kept in groups.

All of these fish can thrive for many years in a healthy pond with good water quality.
There are reports of goldfish living up to 20 years, but the larger species could live even longer.

Water Requirements

Fish which are stocked in ponds are generally tolerant of a range of water parameters. Ideally, ponds should be kept within the parameters shown below.
At times, this may be difficult to achieve as ponds are often subject to external changes.
Frequent water testing is essential to ensure any potential issues are caught early on.

Temperature: between 4-24°C
pH: 6.5-8.5
Ammonia: Zero mg per litre
Nitrite: Zero mg per litre
Nitrate: Not to exceed 20 mg per litre above normal tap water levels
General hardness: Medium-hard (8-18°dH)
Carbonate hardness: Medium-hard (5-15°dkH)

Pond requirements

Ponds for fish should ideally be at least 45-60cm deep, preferably over 90cm for koi and over 120cm for sturgeon.
This ensures more stable temperatures, a cool zone at the bottom in warm spells, and a warmer area at the bottom in freezing winters.
The pond should receive some sunlight as this helps to promote plant growth and to maintain warmer water throughout the spring and summer months.
Shallower ledges around the edges of the pond will help you to grow a wider variety of plants.
Live plants are recommended as they will provide oxygen, remove pollutants and provide food either directly or by supporting microorganisms.
Too much sunlight may cause temperature issues for the species that prefer cooler waters or drive high algal growth.
It is also advisable to avoid any overhanging trees or other large plants which might drop leaves into the pond.
If this is not possible, use an autumn cover net as required.

Goldfish and rudd are suitable for most smaller pond systems. Koi, tench and orfe get larger and it is recommended they are kept in a pond of 4,500 litres or more.
Adult sturgeon require much larger ponds of around 10,000 litres.
Regardless of size, any pond which holds livestock should have a filter as this helps to prevent the build-up of toxic ammonia and nitrite.
A pump or fountain will be beneficial as it helps to circulate and oxygenate the water.

Koi and sturgeon require specialist ponds and equipment including filtration systems, pumps, and UV filters to keep the water clear by reducing the amount of algae floating in the water.
Sturgeon in particular have a very high demand for dissolved oxygen.
Therefore, it is advisable to seek advice from your retailer regarding what is required to maintain these fish before purchase.

It is advisable to cover your pond with a net to prevent wild birds or animals predating on them, especially over winter when there is little shelter from plants.
It may also be worth adding a pond net after adding new fish into the pond as fish are more likely to attempt jumping out during the first couple of weeks in a new environment.

Water testing kits are essential so that water quality can be checked on a regular basis (once a week) to ensure it does not slip below the water requirements stated above.
Click here to shop our Pond Test Kits & Accessories.

Introducing your fish

Before adding any fish, please contact us or speak to us in store to make sure that your pond is an appropriate size for the number of fish you would like to keep.
Check that the water quality in your aquarium is suitable i.e. levels of ammonia and nitrite are zero.
Only increase the number of fish you have in your pond slowly as the population of beneficial bacteria established when maturing your filter need to increase every time more fish are added and feeding increases.
Overstocking or stocking your aquarium too quickly can result in ‘new pond syndrome’.
This occurs when there are not enough nitrifying bacteria to cope with the increased waste from the fish, leading to unhealthy levels of ammonia and nitrite, which may cause fish to become ill or die.

Maintenance

Test the water to monitor the ammonia, nitrite and nitrate levels, together with pH and water hardness every week, especially during initial set-up and after adding extra fish. Any build-up of waste such as ammonia and nitrite can lead to health problems in the fish and some pollutants such as nitrate and phosphate can induce the growth of unsightly algal growth such as blanket weed or ‘green water’. Ensure that any new tap water entering the pond is treated with tap water conditioner to remove any harmful chlorine or chloramine present.

As winter sets in, dead plants and leaves should be removed, and marginal plants should be trimmed back. Otherwise rotting vegetation will break down in the pond and can release toxic gases and chemicals. It is advisable to add a pond heater or floating device to ensure that the surface of the pond does not become sealed with ice. The frequency at which you need to service your filter will depend on your filter type, size and stocking level. However, monitoring the water flow from your filter is important as it will help indicate that the unit is working correctly. If the filter needs cleaning, do not run it under the tap because any chlorine or chloramine present may kill the beneficial bacterial population that has established in the media. Instead, it should be rinsed lightly in the pond water which is removed during a partial water change as this reduces the amount of bacteria which are lost.

If the system has a UV unit, you should normally replace the bulb yearly but check the manufacturer’s recommendations. Be particularly vigilant about monitoring your fish for signs of diseases as the temperature rises. The immune system can be weakened following the cooler temperatures of the winter months. Similarly, it is recommended to re-introduce feeding slowly when temperatures start to increase, as bacterial populations in the filter may take some time to recover.

What to watch out for

All fish will have slight variations in their behaviour or appearance, but keeping an eye on any changes in the following will help to identify any potential problems before they become a real health issue:

• swimming behaviour – hanging at the surface, sitting on the bottom or erratic swimming
• colour – turning a darker or paler colour than normal
• temperament – changes in level of aggression or hiding more than normal
• breathing – gill covers moving at a slower or faster rate than normal
• appearance – development of white spots or fluffy growths, loss of fins or scales
• condition – increase or decrease in body weight and condition
• feeding – reduced intake or lack of interest in food

Feeding

Most pond fish are omnivores, normally feeding upon insects and plant matter. Their metabolism and appetite tends to follow rises and falls in water temperature.
Summer feeding will promote growth and can be used to build up the body reserves of your fish for the cooler winter months, so a high protein food should be used.
In very warm summers, over-feeding must be avoided, so ask your retailer for advice.

As the water temperature falls, it is best to swap to a lower protein, more digestible food such as wheatgerm.
If the temperature falls below 8ºC, it may be better not to feed at all. However, sturgeon should continue to be fed all year round, even at lower temperatures.
It is recommended to re-introduce feeding slowly when temperatures start to increase in the spring.
There are specialised feeds for different species. For example, sturgeon require a high protein and oil content and a sinking pellet whereas goldfish may prefer a more balanced floating feed.

Colour-enhancing foods can be purchased to bring out the colour of your fish. Different sized pellets are also available to suit different sizes of fish.
Pond fish should only be fed what they can eat within a few minutes once a day.
Take care not to overfeed as this can lead to a build-up of uneaten food which breaks down releasing toxic waste into the water.

Click here to shop our range of Pond foods.
If in doubt, contact us for advice on appropriate feeding levels.

Checklist

Before purchase make sure:
1. You have the appropriate equipment and position for the pond.
2. You have researched all the species in which you are interested and your final choices
are all compatible.
3. You are familiar with how to transport and release your fish.
4. You are aware of the daily, weekly and monthly maintenance your pond will
require.
5. You are prepared to look after your fish properly for the duration of their life.

Before purchase make sure:

• The pond is of a suitable size that ideally can accommodate the fish once they are fully grown
• Water parameters are as advised.
• Pond water is cycled and ready to receive fish.

This information is supported by the Ornamental Aquatic Trade Association.
For more information and advice visit www.ornamentalfish.org