Koi are one of the most commonly types of fish that are kept but are not necessarily best kept in an aquarium, koi fish are best suited to ponds. Although Koi can be successfully be kept in indoor aquariums, their tanks must be very large with few other fish to compete for space.

Overall it must be said that it is preferable to keep them in outdoor ponds or tanks that are well filtrated. Koi are also known as Nishikigoi are the national ornamental fish of Japan and date back to before 800 AD. Both in Japan and in China Koi were bred for food by farmers in the Niigata Prefecture in a district North West of Tokyo. These fish formed part of the diet but soon some were noticed for their coloration. These fish were then bred for these colors and it became a hobby that really became serious in the 1800s. This hobby soon developed into an extremely competitive pastime as breeders tried to outdo each other with their fish. Koi have been called ‘living jewels’ and have long been associated with masculine qualities. They are also called samurai or warrior fish, This is not because they fight but rather because of their swimming ability.

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Koi are very friendly fish and will take food readily from the hand, follow owners around ponds and even allow themselves to be petted in the water.

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If you feed a watermelon to Koi carp, they may even let you pet them

Koi fish are not goldfish but are related. They live for an extremely long time and will outlast many other kinds of pets, living 20-30 years with some species surviving up to 100 years. Koi are hardy in the right kind of pond and can grow as long as 80 centimetres if they reach their potential. Currently koi cost from two dollars to well over three hundred dollars for large or special specimens. A Koi can grow from about 4cm to around 12cm in a few years but many will grow faster. The size that you begin with depends on the size of your tank or pond and your budget. Koi are readily available and a good place to start is the Koi Society or club in your area. These organizations are also a good source of information for the beginner. They also hold competitions were you can show your fish if you become that engrossed.

The pond/tank

Keeping fish indoors isn’t easy – you will need a huge tank with an extremely powerful filtration system.

Ponds can be more complex but koi can be kept in quite small ponds however they just won’t be extremely happy or grow to their full potential. The pond should be at least 45 cm (18 inches) in depth but the deeper the better. Try to get it about 10 feet (three metres across). 7 feet will (2 meters) will work but the extra room will make your Koi Carp much happier. For really big Koi Carp you will need to allow anywhere between 150 gallons to 300 gallons (500 litres to 1,000 litres ) for each fish depending on size and type of pond.

Any design is fine and you can landscape it to be as attractive as you like. They are great as part of an outdoor area. Try to allow a shallow area for watching and feeding as this will add to your enjoyment. Also organize a good deep section as well. This will allow the fish to avoid extremes of temperature, especially the heat. It is a good idea to place the pond in some shade as this will stop the heat and direct sunlight will detract from the color of your fish. Choose a design that you think will suit your needs. I recommend a look at a variety of ponds both large and small that will give you some insights into what features you like. Some clubs and organizations offer tours of people’s ponds. These are a good idea as you can get an idea of what works and what doesn’t. You can also get a visual picture of what people are talking about and see how the fish adjust. You can use the photos in this book to get an idea.

Care of Koi

Luckily, Koi are not tropical fish and can be kept in unheated water conditions in most climates.

The best temperature for optimal growth is about 70 degrees (20 Celsius) but they will survive quite well at temperatures between 40 to 90 degrees (4C to 32C). One warning from these figures’ is not to let them overheat.

If you live in a place where ice will form on top of the water, just make sure that there is an airflow in the water, drill a hole in the ice to allow oxygen flow. Koi are very heavy users of oxygen and you will need some form of aeration in the water at all times.

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A Koi pond in Baltimore, Maryland

The best way to feed koi fish is to use the pellets. These are easy to buy and form a complete diet for your fish. They are also made with ingredients that keep your water clean so no harmful bacteria will grow in the water. You can feed your koi other things to spice up the diet and its recommended you do this, for the same reasons in keeping goldfish. They will quite happily eat cooked vegetables such as peas, carrot and pumpkin, breads, porridge, shrimp, crab, assorted worms, cooked egg, lettuce and even bits of meat, not fat. 

It is important to remember that you only need to feed as much as they can eat in five minutes. You can feed twice a day in smaller portions. This is the preferred method of experienced breeders. Koi are the same as all fish in that if you feed too much it fouls the water and this leads to serious problems such as severe algal growth. Try to develop a feeding routine and spend some time with them so that your koi tame down and are happy to see you. This will enable you to enjoy your time with them. Koi can also go for a few weeks without any food at all but you don’t want to try this too soon.

A dirty koi pond – this is what happens when you leave too much uneaten food

Filtration for Koi Ponds

This is a common question about Koi, especially from those who keep outdoor ponds“ I must admit that l have seen unfiltered ponds that seem to work well but I would always recommend that you filter your pond and it is essential for a tank. Filtration is a twenty-four hour business in big Koi ponds and you need to take particular care with the system that you install. Filters remove the visible and invisible wastes and keep the system viable for fish. 

A good system is cheap to run and easy to maintain whereas a poor system is a nightmare you don’t want. The simplest system is one that works on the biological principle of running foul water through gravel or pebbles. These systems work and are easy to maintain. Simple systems of this kind can be made from old 200 litre plastic drums with some simple plumbing. Koi need proper filtration so it is best to seek the help of your local club or fish stockist for help. Get the filter right and it will save you a lot of trouble. 

Also think about your filter before you build your outdoor pond. This will simplify the process and save you a lot of work as you build. If you do this you won’t have to dismantle anything or change your pond. Obviously the larger the pond the more Space and size your filter will be. If you have a swimming pool sized pond and this is not far fetched the filter will need to go somewhere. Plan for this as well. Planning will save you money and time and increase the enjoyment of your hobby. 

If you have converted an old pool don’t be tempted to use the old pool pump. They are not designed to run 24 hours a day and are expensive to run anyway. There are commercially available filters that you can buy straight from the shop. Check out local koi keepers in your area to see if anyone has one and that they are suitable. They can be expensive mistakes if they are unsuited to your area or pond. If you have other keepers who use them successfully it may be the way to go. 

Whether you choose the up-flow or down-flow system of biological filtration is again a matter of taste and which is the best for you. Again, ask around. You will also need to decide on a filtration medium, such as gravel. The system will also need a pump with the correct flow rate. This is important as a biological system needs the right amount of water flowing through it every hour of the day. For the more advanced keeper you will also need to think about such things as the water chemistry of your pond (things such as pH and alkalinity), oxygen levels, algae and oxygenation. 

With outdoor ponds you will also need to be aware of the sprays you use around the house and on plants. It might also pay you to let your neighbors know you have fish so that spray drift does not enter the water from toxic chemicals. This is a sure way to kill any fish.

 


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