How to Introduce Fish Successfully

Fish are the natural addition to the pool, and often the reason for choosing to add a living water feature to the garden. Affinity had been specifically designed for easy and successful fish keeping. For fish to thrive and give you years of pleasure there are a few guidelines to follow.

Set up your Affinity and Inpond All-in-One, making sure to add Bioactive Tap Safe when you fill the pool. With the Inpond running (you can run your fountain or waterfall at this stage), leave it all to settle for at least 24 hours to ensure everything is working correctly and allow the water temperature to stabilise.

Only introduce one or two fish at the start. The trick is to increase fish quantity slowly over a period of three months to allow the life support system to mature*.

*What is a mature ‘life support system’, and why is it necessary?
A healthy pool with fish is maintained by the Inpond ‘life support filter system’. The ‘life support system’ maintains water quality (as well as clarity) by providing an environment for friendly bacteria. These feed on the waste products within the pool. This population of friendly bacteria needs to gradually grow to meet the levels of waste being produced within the pool. The ‘Bioactive’ element of the Bioactive Tapsafe included in the kit helps to start, and speed up, the population of friendly bacteria. The population can be further increased by adding a sachet of Blagdon Bio Start.


The keys to success in establishing a healthy living pool are:

  1. Feeding – Food is the main source of waste products. Whether it is eaten by the fish and excreted as waste, or (as is often called ‘over feeding’) when more food is put into the pool than the fish can eat in 5-10 minutes. Carefully feeding the fish to ensure none is left over, and only feeding once a day for the first few months reduces the amount of waste put into the water.
  2. Quantity of fish introduced – The fish population should be increased slowly over the first few months while the ‘life support system’ matures. Less fish means less food, less food means less waste, less waste is easier to deal with by the maturing population of friendly bacteria.
  3. Partial water changes – During the first three months, as fish are introduced, toxic levels of invisible waste products can build up. To prevent the risk of this, regular partial water changes are recommended (see How to…Fill and Top up Water). This will dilute toxins and help to maintain a healthy pool. The invisible toxins, if not diluted, can be harmful to the fish. Pool fish are generally healthy and easy to keep however, if stressed by poor water quality they can become susceptible to disease.

After three months, by which time the life support system will be mature, fish feeding can be gradually increased, and the frequency of the partial water changes reduced. You will now have a healthy, matured pool.

Careful attention in these early weeks will pay for itself in an easy to maintain, and healthy home for your fish.

If you keep fish in the pool, the pump and filter MUST be run constantly. Water movement from the pump (via the fountain or waterfall) increases essential oxygen in the water for the fish. It also ‘pulls’ the waste from the water into the filter. The friendly bacteria within the ‘life support system’ also require a flow of oxygen rich water to live. If the ‘life support system’ is turned off for more than a couple of hours, oxygen levels will drop and the population of friendly bacteria with be reduced.