Keeping Your Koi or Catfish in a Heated Pond

by Marijn van Haaren & Allan James

 inter in the UK has become increasingly harsh and, unless you look after your fish meticulously, it is likely that they will struggle. To counteract this, we have seen an increasing number of fish keepers heating their ponds. There are, however, stumbling blocks to this plan, but many of these can be counteracted.

Why Install A Heated Pond?
There are a number of reasons why installing a heated pond is beneficial for both you and your fish. Heated ponds will:

• Avoid low temperatures which cause health problems for the fish
• Cause less stress to your fish, making them stronger throughout spring
• Limits immune system damage for the fish
• Allows the keeper to continue their hobby

What About The Costs?
Many of us see the cost of heating a pond as the main barrier to installing one. In truth, there is no set running cost for a heated pond, and you can make it as expensive or as inexpensive as you like. The overall cost is dependent on a number of factors such as size, ambient temperature and location. The amount you pay is dependent on the heating method you choose, so make sure you get estimates before you begin. It is possible to heat your pond for as little as a couple of hundred pounds throughout the entirety of winter. But, the more outlandish your plans become, the more this price will spiral and, if you’re not careful, rising gas and electric prices can make your vision entirely unaffordable. After all, there’s no reason why it should cost the earth, and the overall costs are well worth the results and the enjoyment.

A Pond in your Conservatory?
This would probably be the best of two evils as your conservatory will be heated anyway and might only need a top up temperature wise with some aquarium heaters if you find the water needs a little more heat in the winter months for your chosen species. You could grow specialist water plants which you would struggle in an outside pond and also terrestrial varieties outside of the pond. With this method you could have an overflow pipe which could run to a soakaway under the floor.

Can I Include, Catfish ?
Well, putting it simply, when filling your pond, the world is your oyster. The best way to plan what you would like in your home is to begin with the fish you would like as the centrepiece.
The first catfish that you would think of as temperate/coldwater would be the “Wels catfish” Silurus glanis. It is the only European catfish and Europe's largest freshwater fish and is only one of two catfish indigenous to Europe the other from the same genus, Silurus aristotelis is from the River Akelhoos in Greece. This species looks like the other wels, but its dorsal fin is smaller, and it has just two pairs of barbels. A pond for this large species would need to be at least 20ft x 10ft with a minimum depth of 5ft and a large pipe for it to fit in for cover.
So there is a price to pay literally for keeping a wels in your pond, heated or not. For those who don’t know, the Wels catfish is now a prohibited species in this country, unless you hold a licence to keep them.


Silurus glanis from the Ebro River, Spain. ©

Silurus glanis from the Ebro River, Spain


People often feel that it is impossible to keep fish like the Synodontis of the Mochikidae family due to their specific requirements. This, however, isn’t necessarily the case and, although a challenge, it is one that is both doable and very rewarding especially if it is an inside pond.

If you would like to keep any of the Synodontis species flock of Lake Tanganyika you would need to keep the temperature to the minimum of 25°c (77°f.) and be aware that they will prefer water on the alkaline side of neutral. Other species of Synodontis would need to be kept at least in the mid 70s f. but you have a better choice when you come to the p.H. which can range from 6.0 to 7.5 with no problems.


Synodontis ocelifer

Synodontis ocelifer


The larger catfish of the Doradidae family are another group of fish which could satisfy your needs for a heated tropical pond and have been successfully kept in the warmer climes in the south of England. Again you should read up on your given species and the many forums and groups on the internet are sometimes a good resource to bounce ideas of.



Megalodoras uranoscopus © Graham Layley

Megalodoras uranoscopus





The Compleat Embro Angler

Danny Blundell
Graham Layley


Acknowledgement: Daphne Layley (pers. com)



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