Whats the difference between Koi and goldfish?

Koi (Cyprinus carpio) and Goldfish (Carassius auratus) are both in the same family: Cyprinidae.
Goldfish are much easier to keep than Koi, they are smaller, require less feeding and produce a very small amount of waste compared to Koi. Filtration, although required, can be installed at a reasonable cost and will take up less garden space – needing less maintenance. The variety of shapes and colours of these lovely fish bring a vibrant dimension to your garden space.
Koi require a different approach to that of keeping goldfish. A number of pond owners start off with a pond setup for goldfish and then introduce small Koi, as they have been attracted by the wide range of colours of these beautiful fish. Whilst this can be ok for a short time, it does not take long before these Koi outgrow the filtration system and in some cases the pond that was originally intended for Goldfish only. Koi produce a lot more waste than Goldfish as they process a lot more food. It is essential to have a good filtration system and a pond with a depth of at least 1.2m, preferably 1.8m, and a capacity of at least 7000 Litres. Without a doubt, having a garden pond with Koi adds a splash of living colour to your garden and given time, you will be feeding them out of your hand.

How long can Koi live?

Koi usually live around 20 or 30 years. The oldest Koi on record was named Hanako. It purportedly lived to be about 226 years old. It lived in a pond that was in a stable area (read low geologic activity) and was passed down from generation to generation. Hanako died around 1977.

What kind of food should they eat?

During the summer, when the water temperature is above 16 degrees Celsius, feed your Koi fish a high protein Koi food.  During autumn and spring, when the water temperature is between 10 and 16 degrees Celsius, feed them an easy to digest wheat germ based Koi food.  When the water is below 10 degrees, stop feeding your Koi. Koi digestion slows down as the temperature drops so any food not digested by the fish could be fatal.

How big do Koi get?

This depends on the parent stock and country of origin. Japanese Koi can grow to a metre or more in length.

Does the size of the pond hinder a Koi's growth?

The size of a pond will not stop a Koi from growing. Pond size along with other factors like health, feeding, water temperature, and water quality all affect the speed of their growth. A Koi will keep growing until it has reached its genetically predetermined size.

Can Koi and goldfish live together in the same pond?

Yes, Koi and goldfish are both docile and can live together.

How many Koi can I keep?

The following GPK (gallons per Koi) rates based on size: This is a guide only.

• Small Koi (2″ – 8″): 100 – 150 gallons

• Medium Koi (8″ – 14″): 250 – 300 gallons

• Large Koi (14″ – 24″): 400 – 500 gallons

• Jumbo Koi (24″ – 36″): 750 – 900 gallons

The number and size of Koi you can keep is governed by the quantity and quality of food you are feeding them, and what your filter can process. Most reputable filter manufacturers will state feeding rates. If this is not known then Nitrite levels are the most important indicators of overstocking. If your Nitrite levels are constantly in excess of 0.2 mg/l you need to remove some of your fish, or introduce larger or additional filter systems. In addition to this, overcrowding your pond could cause stress in your fish and reduced their immune systems. This could result in outbreaks of white spot and other parasitic infestations. No two ponds are the same, so these are just guidelines to help you decide on how many fish you can keep in your pond.

What is the temperature range that Koi can live in?

Koi can live in water that ranges in temperature from 4 degrees Celsius to 32 degrees Celsius. They won’t thrive at the extreme temperatures though.

Can Koi stay in the pond during the wintertime?

Koi can stay in the pond as long as you keep a hole in the ice to allow fresh oxygen to enter the water and carbon dioxide to escape.  Never break the ice by hitting it with a hammer as this will shock the fish. Covering your pond with acetate sheeting during the winter months will significantly help. Very low temperatures may effect the swim bladder of your fish, causing irreparable damage.

Where do Koi Hut's fish come from?

We purchase our Koi Carp from specialist Koi farms in Japan, mostly from within Niigata prefecture. See below for a map of our Koi breeder’s farms.


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