Fish Care

Preparing your pond for fish

Once you have installed your new pond there are a few steps you need to go through to create a healthy, balanced pond that is suitable for your fish.

Firstly you need to understand the concept of a healthy balanced pond. A balanced pond has adequate amounts of plant life including oxygenating plants, emergent plants and plants that give a bit of surface cover. eg. water lilies. It is always a good idea to get these plants in about 2 weeks before you introduce your fish. This will allow the plants to get a little settled and established before your fish arrive. Having biological activity in your pond is crucial for the health of your fish. Bacteria such as those contained in Clearpond Bio Starter  will ensure you can set up your pond in a weekend and fast-track the normal biological process. This bacteria will convert the fish’s waste which contains ammonia and is toxic to the fish into nitrites which are still dangerous to the fish but not as toxic as the ammonia. A second bacteria will convert the nitrites to nitrates which are no longer dangerous to the fish and which are able to be consumed by the water plants. It is a good idea to do a simple pH water test just to be sure the pH is as close to neutral as possible to prevent fish diseases.

How many fish can you have ?

A good rule of thumb to follow is that for every square metre of surface are your pond has (providing it is over 30cm deep) you can have 50cm of fish, if you measured them all nose to tail. This equates to say 10 x 5cm fish or 5 x 10cm.

Introducing your new fish into your pond

It is now time to introduce your fish. The fish you buy will be supplied to you in a plastic bag that is tied up with an elastic band. The bag should be floated on the surface of there new home for approximately 20 minutes to allow the water temperatures to adjust so that when you release your fish they do not get a shock with the change in water temperature. After the 20 minutes has elapsed it is time to slowly release your fish from the bag.

Keeping your fish healthy

The general health of your fish is directly related to the health of their environment. The most common cause of fish problems is high nutrient levels in the water which turn the water acidic. High nutrient levels are caused by several factors, excess fish waste, excess un-eaten fish food and rotting vegetation. A good amount of oxygenating plants such as Elodea or Vallisneria will help to minimise this build up of nutrient as they will use a large amount to grow and spread. So if your pond water is balanced with adequate amounts of plant stock, reasonably clear and circulating with a pump, you could guess that your fish are going to be healthy. There are several factors that can change the health of your fish, some are external, some are internal and others are seasonal.

Good circulation and filtration of the water also helps to keep nutrients at an acceptable level. Biological filters in particular are excellent for performing this task. They work by housing a colony of good bacteria which break down and consume the organic matter. There are also Bacteria cultures available in a powder form to perform this same task. So keeping a healthy balanced pond is important, don’t over feed your fish, keep a good amount of plant life and leave your pump and filter running as much as possible.

Seasonal changes and how they effect your fish

As the season changes so does your pond, not only water and air temperature but the amount of light that gets to the water, the plant life coverage and the metabolism of your fish.


This is the beginning of all the action for a garden pond. The plants are beginning to shoot and your fish are starting to become a little more active. As the water temperature increases so too does the metabolism of your fish. This means that they are starting to require a bit more food than you have been feeding them over winter. It is also the time that all the dead leaves and rotting vegetation that has been sitting inactive on the base of your pond start to create a food source for algae.

As this increase in available nutrient develops you may get algal blooms popping up. This is a great time to scoop as much of the leaves up as possible and give the pond a bacteria treatment as an added boost.


The greatest time of enjoyment for you as the plants are all flowering, the fish are darting all around the pond and the water is clear, hopefully. If you didn’t get around to cleaning your pond up (not out) in Spring you will find that the algae problems are getting a little worse.

The water is heating up and your fish need a little more food. Make sure that at this time of the year you are feeding your fish every second day and only as much as they will eat in 3-5 minutes. Otherwise the excess food will fall to the bottom of the pond and feed the algae. Also there are a lot of insect and mosquito larvae that your fish will eat.

Remember that as the temperature increases over summer the water will hold less oxygen so you must ensure that your pond has adequate aeration.


The water is beginning to cool down now so slowly start to reduce the amount of food or frequency with which you are feeding your fish. Drop back to about every third day. As the surrounding trees begin to drop their leaves so to do the water plants such as water lilies. It is good practice to get as many as these out of the water now so as to minimise the amounts after winter.


The quiet time for your pond and fish. The fish will slow down to such a point (when the water is under 10 degrees ) that their metabolism almost stops. So a little food once a week is adequate. You may even find that this won’t be eaten, in which case use your fish net to remove any uneaten food after about 10 mins. This is the best time of the year to make any alterations to your pond, re-pot any water plants or give your pond an entire clean out. Keep in mind that you should only ever totally clean out your pond if there is a large amount of silt or rotting vegetation that has built up over the last few years and it is not possible to remove it any other way.