Frequently Asked Questions

Whether you are a beginner or expert koi keeper, if you have a question about keeping koi that you need a quick answer for, one of our customers may already have asked and we have tried to summarise some of the most common questions below. If you can’t find the answer to your question here please do get in contact here and we will come back to you as soon as we can.

Koi, or Nishikigoi which translates to brocaded carp are large ornamental fish that are very docile animals that when kept under the right conditions will be one of the most rewarding creatures an individual can own.

When selecting Koi there are numerous criteria that makes a Koi ‘Perfect’ however these ideal criteria might not appeal to your personal taste. It is important therefore to purchase fish that you yourself will enjoy to see swimming in your pond.

Despite being two distinctly separate species many new hobbyists often get confused identifying the two, here are a few easy signs to look for.

  • Koi have small barbels on either side of their mouth, these are absent on Goldfish.
  • Koi reach sizes three times greater than Goldfish.
  • Goldfish have a detached dorsal fin just before the tail, whereas on Koi it is attached to the full length of the body.

We offer a large variety of Koi and can obtain most varieties on request. Contact a store for more information.

All Koi listed by KoiKeeper are all sourced directly from Japan, where we purchase fish from renowned breeders and bring them to the UK for you.

All Koi are screened and treated appropriately for infection, parasites and disease prior to sale.

To purchase Koi from KoiKeeper, please contact the relevant branch quoting the code of the fish you are interested in and we will get back to you as soon as possible

When purchasing a Koi we will handle all your concerns for transportation, using oxygen, multiple bags and boxes where necessary to give your new fish the most pleasant journey possible. It is then your responsibility to make sure you arrive from point A – B as soon as possible.

Contrary to common belief Koi are not made of porcelain and are very forgiving animals. The key to maintaining a happy and healthy Koi pond is a combination of good practices and routine. This includes but is not limited to, cleaning your filter frequently, partially changing the water and water testing. If you have any concerns with your Koi do not hesitate to contact us.

During winter months when the water is cold, your fish might begin to refuse food and sit low to the bottom of the pond, in these instances Koi can go for long periods of time not needing to feed and can rely on naturally occurring food in the pond. However if your fish still surface for food during cold periods it is advised that you continue to feed them a suitable food such as wheatgerm.

The value of a Koi can be broken down into many factors, including things such as the manner in which the fish moves in water, bone structure, shape, skin quality, potential for the future. For the many different varieties of Koi there are many more factors.

Koi are not predatory and are quite the gentle giant so it would be unusual for larger Koi to attack smaller fish.

We would recommend a minimum of 90cm in depth for Koi. The hobbyist can construct a deeper pond but just remember to keep it at a manageable depth for yourself to work on.

Koi ponds need to be constructed smart. Take your time researching the cost of labour, materials and adequate equipment for your Koi pond to build the best possible pond within your budget.

Most Koi live for on average twenty years but have been known to live in excess of thirty!

To get the most of your Koi it is best to buy a good quality brand food that uses quality ingredients, using poor quality food can not only effect your water parameters but also the quality of your fish.

Depending on the lineage of the fish, some Koi have the potential to reach sizes in excess of 100cm!

Smaller volumes of water are certainly harder to keep clean, and because Koi are such large messy creatures that can foul small bodies of water quickly this will impact their growth.

Many hobbyists house the two animals together without issue.

Before purchasing Koi we recommend that your pond be a minimum of 1000gallons as to allow for the full potential of your fish, beyond this the number you can keep will depend on existing stock, your filtration and the actual volume and footprint of your pond.

Koi can survive between 2 – 30 degrees Celsius.

Yes they can, however you should take precautions to insulate the pond and prevent it from freezing over to make their winter months as comfortable as possible. You will also need to maintain your routines and water testing during the winter.

Breeders in Japan have very strict criteria for their fish and endeavour to produce fish of a greater quality than anywhere else in the world, with bloodlines, techniques, expertise and the perfect environment for raising Koi stretching back decades.

Most Koi will be contempt with being fed at least once per day, however they will eat much more frequently if you desired to feed them more often. Feeding them more frequently has the potential to increase the rate at which your fish grow but at the cost of increasing the maintenance you will be required to preform on the pond to keep things ticking over healthily.

The manufacturer of a filter will list it’s specs with the unit you purchase detailing how well the unit will preform on a pond after multiple variables such as sunlight, water volume and stock. 

Ponds with bottom drains which rely on gravity fed filtration are much more successful than those without, where possible it is best to design your pond to include one but is not necessary.

You can certainly try! In most instances however Koi will uproot or attempt to eat any vegetation in a pond.

There are several salt ‘milestones’ that can be used to treat a pond ranging from 0.30% – 0.90% however it is always best to seek advice before using salt. 

If you are using salt in your pond it is important that you have a tool designed to measure the salinity of your water so that you may keep track of it, blindly dosing the the pond can cause more harm than good.

Be on the lookout for any unusual behaviours or signs such as your fish being lethargic, clamped, grey in appearance, pinkish skin, rubbing against objects and wounds or growths appearing on the body. If you do notice anything odd about your Koi the first step is to test your water.

The clarity of water does not determine it’s quality, the clarity of pond water is for us to be able to appreciate our Koi. If your water is turning green, it is best to add a strong UVC unit so that you can continue to enjoy your fish.

No, only treat Koi as and when they need to be treated. If you suspect parasites the only way to be certain is to scrape your Koi and inspect the mucus under a microscope. Although this sounds daunting and complicated it couldn’t be easier and doesn’t require expensive equipment. A basic student microscope will suffice and will serve as an extension of your hobby, making you a better KoiKeeper!

As temperatures fluctuate throughout the year, the metabolic ability of the your fish will change and their diet must change in accordance in order to keep them healthy. It is good practice to always keep a pond thermometer on hand to observe these changes in water temperature.

Like most fish Koi require clean, healthy, dechlorinated water. This would require 0ppm Ammonia, 0ppm Nitrite, Nitrate not exceeding 50ppm and a stable kH and alkaline environment. Ideally between 6 – 10 dkH but can be much higher.

The best practice is a minimum of once per week and continuously after spotting any issue or when treating the pond.

The best filter for a Koi pond will be determined by the individuals budget, however a combination of drum, moving bed and showers are proving to be the most popular and effective forms of filtration amongst Koi Hobbyists.

Because there’s so many variables there is no strict rules when stocking a Koi pond. With every pond being so unique it is best to contact a store to discuss stocking your pond.