The Start of the Koi Season is here!

Now that the days are getting longer and (with a bit of luck) the days brighter, our thoughts are turning to our ponds. Whether you’re keen to get back into your pond after the winter, or you’re raring to get going on a new project ready for the summer, this time of year is prime time for getting stuck in.


A major area within the pond business is the keeping of koi carp, the stunning ornamental variety of the common carp Cyprinus carpio. Despite being farmed for food in East Asia for centuries, common carp weren’t bred for colour to develop koi as we know them today until the early 1800s in Japan. Now available in a plethora of colour varieties with a price tag ranging from just a few pounds to thousands there truly is a variety to suit anybody’s taste and budget.

Whether you’re a seasoned pond keeper looking to take the next step or a newcomer to aquatic life, we’ve put together some information to help you hit the ground running this pond season. 

Start of the koi season

Things to Consider


Koi are a little more demanding than goldfish, and it’s important to ensure that your pond and filtration system are big enough to cope with this demand. Before purchasing any equipment or breaking any ground you’ll need to ask yourself some questions:

How many fish do you want to keep? Do you want just a few feature fish, or do you want a large variety? Although often only a few inches in length when purchased, koi are capable reaching sizes in excess of 1m (just over 3ft) in length, and so it’s important that they’re housed in a suitably sized pond.

Next, you’ll need to consider filtration. Koi can be extremely messy fish, producing a lot of waste and often forage through the dirt on the bottom of the pond, stirring it up. Your filtration should turnover around 2-3 times the total volume of your pond every hour to cope with this demand. This can be provided be either pressurised or box filters.

Box filters provide a greater volume of biological filtration, but need to be positioned above the pond in order to return the water via gravity, whilst pressurised filters can be buried in the ground up to the head of the unit, but have a smaller volume available to house filter media.

Both types of filter come with the option of UV sterilisation. This breaks down algae cells, causing them to clump together into larger particles so that they are more easily removed by the filter media, and also kills disease causing bacteria, helping to keep the water clear and healthy.

Our full range of koi filtration systems can be viewed here

When can I begin to add Koi to My Pond?

Whether you’ve already got a pond with room for some new additions, or you’ll be adding your first lot of fish this season, it’s important that your fish are added at the right time. This is because your fish are likely to come from a warmer environment in store, such as a greenhouse or even an indoor aquarium.

The general rule of thumb here is when the water is above 10 degrees Celsius, (normally Mid-April to Early September); it’s safe to add new fish.   However, it is always best to monitor your pond temperature over a week or so to ensure that this consistent, as one warm day may be followed several colder days, and your koi won’t have time to acclimate to the cooler temperature of the water. 

Feeding After the Winter

As the weather begins to warm in the spring, you’ll notice that your fish become more active. Their metabolisms will begin to speed up and after a few consecutive days of warm weather, you can begin to start feeding again. It’s important that you only feed when there’s an extended period of warmer weather. This is because the protein in fish food is harder to digest, so the fish need a few days of warmth to get their metabolism up to speed.

A fully balanced diet should be provided. A wide range of pellet feeds are available to provide the base for this, but you should also consider supplementing this to really get the best out of your koi. Their diet can be supplemented by insects (crickets or mealworms are a good choice), whilst dried krill is also very popular, and the carotenoids in krill will really optimise the colouration of your koi. These should be used sparingly (no more than 1 or 2 per fish), however as they’re very high in protein. Aside from these, koi will also relish green matter such as spinach, fresh, shelled peas, or cucumber.


After taking into consideration all of the above, the final thing (and most exciting) to consider is the type of koi you’d like. There is a multitude of colour varieties, over 20 in fact, to choose from.  From the ubiquitous ghost koi with an attractive black body and white/yellow sheen to the highly sought after Sanke variety; a pure white fish with eye-catching black and red markings; there is a variety available to appeal to almost anybody. 

This information should give a head start in the pond season, and we wish you every success with your koi this season!