New Pond Syndrome
Author: Bernice Brewster
Ponds are a very attractive feature in any garden and can be a source of great pleasure through the summer months, when the fish are active and the water encourages a wealth of wildlife such as frogs, newts, dragonflies, hedgehogs and very occasionally muntjac deer, to visit. An established pond may have an assortment of fish and aquatic plants, with sparklingly clear water but what of a new pond? One of the commonest problems encountered with any new pond can be directly related to the water conditions, often termed 'water quality'.
Often the first indication of a problem is when fish start dying for no apparent cause or succumb to a variety of diseases such as white spot, ulcers, fungus and fin rot, which are secondary infections arising from stress caused by the poor water conditions. The poor water quality associated with a new pond has been called 'new pond syndrome'. It is very common to fill a new pond and test the water, then add the fish. The problems with the water quality actually begin after the fish have been added to the pond.
How does adding fish to a new pond cause a problem?
Fish produce waste in the form of ammonia, which in an established pond is either utilised directly by the aquatic plant life, or is broken down to nitrite and then nitrate through the activity of naturally occurring bacteria and other micro-organisms encouraged to grow in the biological filtration system. It is the presence of ammonia and nitrite in a new pond system, which contributes to the poor water conditions, which ultimately leads to the fish becoming sick or even dying.
In a new pond, the aquatic plants may take several weeks to become established and begin to grow. During this time, the plants are unable to consume the ammonia waste produced by the fish, which begins to accumulate in the water. As the ammonia builds up in the water, it poisons both the aquatic plants and the fish, so that neither thrive.
A pond which is fitted with a biological filter may take several months before the water quality becomes acceptable after stocking with fish. Once the fish have been added to the pond, ammonia will gradually build up in the water, until it reaches very high concentrations. The quantity of ammonia dissolved in the water encourages Nitrosomonas species of bacteria to grow in this abundant food source. The Nitrosomonas bacteria break down the ammonia to nitrite. As the ammonia is consumed it begins to decrease but the concentration of nitrite increases at the same rate, leading to further water pollution.
How do I know if ammonia or nitrite are polluting my pond?
Ammonia damages the delicate gills and other vital organs. The damage to the gills often causes the fish to be found near any water inlet, where they are seen at the surface,
breathing heavily. Nitrite is a skin irritant, causing the fish to rub and scratch as well as affecting the red blood cells, making it difficult to absorb vital oxygen from the water. Unfortunately, neither ammonia or nitrite are coloured or have any detectable odour and the only way to be sure they are not polluting the water is by using water test kits, readily available at Prestwood PetZone
These test kits are easy to use and can quickly identify any water quality problem. It is best to test the water on a weekly basis once fish have been added to the pond in order to prevent the health problems associated with the deteriorating water quality.
What should I do if I find ammonia or nitrite polluting my pond?
In the event of discovering either ammonia or nitrite polluting the pond, it is important to undertake a series of partial water changes. It may be necessary initially to change up to 25% of the water on a daily basis to reduce the concentration of ammonia or nitrite. Although tap water is treated with chlorine to make it suitable for human consumption, this is the best water source for water changes. Rain water is not suitable for filling or topping up the garden pond. Tap water has percolated through underground sediments and contains an assortment of essential salts and minerals, important for the welfare of the fish. Rain water does not contain any salts and is also mildly acidic, which makes it unsuitable for adding to the pond. In order to remove any harmful chlorine or other tap water additive, a water conditioner should be used to ensure
the water is suitable for the fish. It is important to continue monitoring the pond water on a regular basis until ammonia and nitrite are no longer detectable.
Should the water be affected by high concentrations of either ammonia or nitrite, extra air should be added to the pond in addition to the partial water changes. The air will encourage bacteria that breakdown the ammonia and nitrite to thrive and help the fish to survive. It is also a good idea to just reduce the amount of food offered as too much feed will cause the fish to produce more waste, which in turn can lead to further pollution of the water. Always remove any uneaten food or pieces of dead plant as these can also contribute towards polluting the pond.
Will the fish recover if their gills have been damaged by ammonia or nitrite?
The answer to this question is 'yes', providing the water quality improves and remains good, once the 'new pond syndrome' effect of ammonia and nitrite pollution has subsided. Fish have the most amazing ability to recover from water pollution, severe injuries or other environmental
insults.
Why should I test the pH of the pond?
The pH is purely a measurement of the acidity or alkalinity of a substance. The pH is measured on a logarithmic scale of 0 - 14, where pH 0 - 6.99 is acid, pH 7.0 is regarded as
neutral and pH 7.01 - 14 is alkaline. To give some idea of how these pH values relate to everyday life, the following are a list of substances we regularly handle, or even consume, with the pH.
Strong battery acids: pH 0 - 1
Lemon juice: pH 2
Orange juice: pH 4
Milk: pH 6
De-ionised or distilled water is neutral at pH 7.0 as it does not contain any minerals or salts.
Egg white pH 8
Milk of Magnesia pH 10
Agricultural lime pH 13
Caustic Soda pH 14
It may be realised the extremes of pH are the most caustic and cannot support life forms. The ideal pH for pond fish is between 6.5 - 8.5 for healthy growth, tissue repair and reproduction. It is important to realise the pH is not a fixed value and will fluctuate throughout a 24 hour period through the activity of plants and fish respiration.
The pH influences how poisonous ammonia can become in alkaline water. Where the water is alkaline and with increasing temperatures, the ammonia becomes much more potent and dangerous to the fish. Even though there is only a little ammonia polluting the water where it is alkaline it is very poisonous to the fish and partial water changes need to be made. By contrast, nitrite is more harmful in acidic, or soft water.
How can I prevent my fish from suffering 'new pond syndrome'?
The best way to prevent the problems of new pond syndrome from arising is to buy just a few fish, perhaps no more than six and add these to the pond. After putting the fish into the pond, regularly test the water for ammonia and nitrite. Providing the water quality remains good, that is, free of ammonia and nitrite for roughly 14 - 21 days, then a few more fish can be bought and added to the pond and the process of regularly testing the water repeated. If there is any form of pollution with ammonia or nitrite then new fish should not be put into the pond. The fish in the pond with some ammonia or nitrite will have tried to acclimatise to these unfavourable conditions but new fish will have come from the good water conditions in the shop, into this
unsuitable water and usually they die quite quickly. Often other fish begin to die and soon this leads to the misconception that a sick fish has been introduced to the pond.
How many fish can I have in my pond?
As a rule of thumb, the number of fish a pond can hold is based on the surface area of the pond, allowing one square foot of water surface for every two inches of fish - including the tail. This allows for the fish to thrive and grow as well as reproduce.
Just following these few simple guide lines can help you to enjoy your pond from the first day the fish are added - and who knows what it might lead to!
Copyright Pets Parade Ltd. 2000