Types of fish


Koi fish are essentially an ornamental domesticated version of the common carp, and are sometimes known as ‘Japanese Carp’. They originate from Eastern Asia, Aral, Black and Caspian Seas. They are closely related to goldfish. A koi is considered a symbol of love and friendship. They are generally the most popular fish in the world to keep in ponds.

Koi are freshwater, bottom dwelling fish, capable of living in a wide range of conditions. It is generally thought there are THIRTEEN different classifications of Koi. The Japanese classify koi according to various features, including colour, pattern, scale type and arrangement. However, within each classification there are different types of Koi. Koi come in many different colours and patterns, the more common colours are white, black, red, yellow, blue, and cream.




01. Tancho Single crowned Koi with a pattern on its head.
02. Kohaku White koi with a red pattern.
03. Showa A white and red koi with black bands across the back and head.
04. Taisho Sanke White koi with red and black markings.
05. Bekko A koi which has a red, white or yellow solid body colour and black markings.
06. Utsurimono Often confused with the bekko this is a black koi with white, yellow or orange markings.
07. Asagi A blue/grey scaled koi with an orange or red belly.
08. Shusui A cross bred koi between an Asagi and a Doitsu, they have large scales running down their back and sides.
09. Kor A white/red koi with scales showing only in the red markings.
10. Hikarimoyo – mono Any colour of koi with metallic scales.
11. Hikarimono A single coloured metallic koi.
12. Hikari Utsurimono Metallic showa and utsuri koi
13. Kawarimono All other metallic koi which do not fall into the above groups.
Why not check out this Step-By-Step Guide on Starting The Koi Hobby!

Koi do not breed true, so there are constantly new classifications of koi being introduced. Koi fish grow very fast. An average Koi can grow to 24 – 36 inches long! The size of the pond, the amount of aeration, and feeding methods will affect the growth of the fish. It is not uncommon for a small Koi to grow 2 – 4 inches a year in a backyard pond. In their first year koi will grow about 10-20 cm, the second 24-30 cm, and in the third 37-40 cm. If they are kept well, at the fifth year, total length of the fish will reach 45-50 cm, and by the tenth year will be 55-70 cm. Record sized koi have been reported with 1.53 metres in length and 45Kgs in weight.

Koi are an omnivorous fish and will often eat a wide variety of foods, including peas, lettuce, and watermelons. Koi will accept many foods thrown to them in their pond, but many of these are of little or no nutritional value and may even harm the fish. Brown bread is acceptable, but white bread contains a mild form of bleach, which could harm the Koi. Be aware that foods such as beans, peas or corn do have a shell like skin which can cause an irritation to the Koi which may not be able to digest those shells – but many Koi keepers do feed such foods and of course the Koi will show much enthusiasm for them when they are fed such foods. Koi will take lettuce leaves and may also eat duckweed and other pond plants around their pond (with the exception of blanket weed, which is too coarse for them to pull off the sides).

Koi food is designed not only to be nutritionally balanced, but also to float so as to encourage them to come to the surface. When they are eating, it is possible to check koi for parasites and ulcers. Koi will recognise the person feeding them and gather around him or her at feeding times. They can be trained to take food from the human hand. Koi also welcome a variety of live foods, including worms etc. Earthworms can be fed to the fish all year round and are high in protein and soon become a favourite treat – and this is another way to gain the affection of your Koi.

In the winter, their digestive system slows nearly to a halt, and they eat very little, perhaps no more than nibbles of algae from the bottom. Their appetite will not come back until the water becomes warm in the spring. When the temperature drops below 50 degrees Fahrenheit (10 °C), feeding, particularly with protein, is ceased or the food can go rancid in their stomach, causing sickness.

Most Koi fish live for nearly forty years, and some live even longer than that.




After planning the construction of your garden pond, you will have already considered the size of pond you have room for in your garden. In a typical first pond there will be around a dozen small (10–12in) Koi, allowing room for growth. The bare minimum of equipment needed includes a circulatory water pump, a filter, an air pump and UV unit for clarity – all with associated pipework. Labour is a large part of the cost of pond building, but if you do the groundwork yourself you could keep costs to a minimum. Koi are cold-water fish, but benefit from being kept in the 15-25 degrees C (59-77 degrees F) range and do not react well to long cold winter temperatures, their immune system ‘turning off’ below 10 degrees C. Koi ponds have a metre or more of depth in areas of the world that become warm during the summer. In areas that have harsh winters, ponds that are a minimum of 1.5 metres (4 1/2 feet) deep are recommended.

Health and size
Look at the quality of the water, and how the fish are behaving, never rush and buy the first Koi that takes your eye. Ensure that everything is ok with both the fish and their home. Take your time to do this; otherwise it can result in you taking the fish home only for it to die within a few days. When purchasing a Koi fish for your pond, it is less expensive to purchase one that is still a baby. The older the fish, the more expensive they are. Also, if you purchase your Koi fish as a baby, you will have a better chance of teaching it to eat from your hand. These fish are very smart, and are a wonderful way to relieve stress in your life. Sitting by your garden pond, watching your Koi fish swim will bring you a feeling of serenity and peace, and will become your favourite place to unwind after a hard day.

Transporting your Koi home
Unless you live very close to the dealer, you will need to have your Koi packed in a suitable good quality plastic bag (size depends on size of fish), for safe travel. Make sure that the dealer uses fresh oxygen to ensure that the Koi has plenty of air to breath on their journey home. The bag should be sealed with elastic bands to ensure that none of the water or air in the bag escapes. In addition, a box for your Koi is recommended as this will stop the bag rolling around in the car. Always place the box across the car where possible, not length ways as this prevents the Koi, especially the larger fish, from banging their noses during the journey home. In addition use a blanket to cover the box, as this helps by blocking out sunlight. It is advisable to keep the fish as quiet as possible during their journey.

Introducing your Koi to your pond
Once you get your fish home, NEVER simply open the bag and pour the contents of the bag including the fish straight into your pond. Always float your Koi in the bag that they are sold in, on the top of the water as this allows the temperature in the bag to acclimatise to the same as the water in the pond. Normally this takes around 20 minutes, sometimes longer if there is a big difference in the temperatures in the bag to that of the pond. Once the temperatures are equal, then it is best to pour the Koi and its water into a large bowl after carefully removing the elastic band from the bag. Then using a suitable handling net or Koi Sock, transport the fish into the pond. You should always try to avoid pouring the water in the bag that you have just transported your Koi home in into the pond as this water may be contaminated. It is advisable to dispose this water down a drain or sewer.
Unless you are absolutely sure of the health of your Koi, it is advisable if you have the facilities to quarantine your fish between 2 and 3 weeks in a separate container or pond with aeration and filtration.
Your new Koi may not eat anything for up to three days after being introduced to your home; this is normal behaviour and is not a cause for concern.



Rivalling Koi, are goldfish. They are possibly the most commonly kept garden fish, as they are small, inexpensive, colourful, and very hardy. They generally have a long lifespan. In a pond, they can often survive in icy weather conditions when ice forms on the surface, as long as there is enough oxygen remaining in the water and the pond does not freeze solid.



For the ultimate comprehensive Goldfish guide why not look at Goldfish Secrets! 

The perfect habitat for goldfish is a small to large pond, although the depth should be at least 80 cm (30 in) to avoid freezing. During the winter months, goldfish will become sluggish, stop eating, and often stay on the bottom of the pond. This is normal goldfish behaviour and they will once again become active in the spring. A filter is important to clear waste and keep the pond clean. Plants are essential as they act as part of the filtration system, as well as a food source for the fish. They also raise oxygen levels in the water. They don’t really eat plants; just nibble on them a bit. so your pond plants will be safe from them.

Goldfish are very sociable and can be kept amongst most other cold water fish. Compatible fish include Rudd, Tench, Orfe and Koi. It is advisable that you keep goldfish in groups or at least a pair. Ramshorn snails are a helpful addition to goldfish in a pond as they eat any alga that grows within it. It is also important to introduce fish that will eat any excess goldfish eggs in the pond, such as Orfe.


The common goldfish is normally a very evenly pigmented fish with short and sturdy fins and tail. It is often found in a number of different colour variations such as white and black markings appearing on top of the original golden colouration.

The Comet has been bred for a long tail fin, which in larger specimens may sometimes be half the length of the whole body. Comets are rarely one colour, but often have white anfd red patterns that are more pronounced when viewed from above. Furthermore, the comet’s colour is usually more red than gold.

The Shubunkin is a very colourful, hardy fish and one of the most common pond fish. They originate from China and are part of the Goldfish family sharing many of its characteristics such as its shape and growth rate. Shubunkins are best kept in a group though they are a friendly fish that will live well with other species.


Some fancy goldfish are more distant relatives to the common goldfish; they have been so inbred that they may not withstand life in the typical British outdoor pond, especially during extreme weather conditions.
Oranda, Black moor, Fantail, Lionhead, Celestial Eye



Golden or Blue Orfe are fast growing, very active and a welcome addition to a garden pond. Although they are suitable for ponds, they do have slightly different requirements to goldfish. Orfe thrive well in faster moving water that is highly oxygenated. As they are a surface dwelling fish, therefore very oxygen dependant, ponds suitable for Orfe, should be well filtered, and oxygenated. Although they can survive in still water, they are much happier in moving water. Orfe can grow to lengths in excess of 24 inches (60cm), therefore they do require more space that goldfish. Orfe need to be kept in small shoals. They will feel much more secure, therefore the general health of the fish will be much improved. Orfe like a varied diet, consisting of pellets, stick, and flaked dried preparations. This fish will also be more than happy munching on small larvae in the pond.

Rudd are a fantastic alternative to Orfe if you have a smaller pond. Rudds are acclimatised to the British weather and therefore are a hardy fish. They are a smaller growing surface fish which needs less oxygen. Rudd generally only achieve a size of 5-6 inches (12-15cm), however, they can get larger than this in large well filtered ponds.. Similar to Orfe, Rudd live much happier in small shoals. Rudd also like a varied diet, consisting of pellets, stick, and flaked dried preparations. They also like to feed from small larvae in the pond.

Gudgeon are very attractive and peaceful bottom feeding fish. They are also much acclimatised to British weather. These small growing fish will rarely reach lengths any longer than 8 inches (20cm), making them perfect fish for ponds of all sizes. Being bottom feeding fish, gudgeon will assist the pump to remove waste from the floor of the pond. Due to their feeding habits, gudgeon do require a different diet to most ornamental species. Although they will graze on the pond floor for larvae, small worms, and insects, it is a good idea to put sinking foods into the pond, to make sure they are well fed. Gudgeon are a very hardy fish and can be kept with much larger species without the problem of bullying. Although you will not see a massive amount of these fish once they hit the bottom, they are very beneficial to the pond, and a must for all garden ponds. Gudgeon like to live in small groups.

are peaceful bottom feeding fish. . Tench are acclimatised to British weather. Although when living in lakes and large pools they grow to excess of 12 inches (30cm), rarely will they get as big as this in most garden ponds.Whilst it is a bit of a myth that tench will clean the bottom of your pond, they will disturb the silt and debris at the bottom, allowing the filter system to remove the waste more efficiently. Tench will thrive in well filtered large ponds, and are not ideally suited to small goldfish ponds. Tench are at their most happiest with sinking foods, and love scavenging around the bottom for worms and algae. The most common Tench are green, although golden and red can be purchased.