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Creating a suitable environment

To own Nishikigoi, you would first need to create a suitable environment. You may choose to raise them in a garden pond or in an aquarium.


Size 10t~30t
Depth Ideally 1.5m (1.65 yards) deep. The feeding station should be at least 60 cm (24 inches) and the deepest area should be 1 m (1.1 yards) at a minimum.
Location Ideally at a place where there is sufficient sunlight in the morning. The sun allows the generation of oxygen and prevents the water temperature from dropping in the winter. However, too much sun causes the water temperature to rise which decreases the amount of dissolved oxygen, so caution is required.
Water Temperature Ideally at 24~26 deg C (75.2~78.8 deg F). Nishikigoi are temperate freshwater fish and can adapt to water temperature of 8 ~35 deg C (46.4~ 95.9 deg F), but water temperature suitable for them is 20~28 deg C (68~82.4 deg F).


Size Larger than 90cm (36 inches)
Location A flat place with a firm base and where there is no exposure to rain, thunder, and direct sunlight.
Equipment Since aquariums hold only a limited amount of water, water quality is variable, so a system with high filter efficiency is needed. A 3~5cm (1.2~2 inches) layer of clean pebbles (5mm~1cm (0.2~0.4 inches)) at the bottom of the aquarium work much like a filtering media.
Water temperature 20~28 deg C (68~82.4 deg F) is suitable, 24~26 deg C (75.2~78.8 deg F) is optimum.

Daily care

Nishikigoi are known to be very adaptable and easy to care for, but they do require day-to-day care. Feeding, water quality control, and health control are the three important points in raising Nishikigoi.


Nishikigoi are omnivorous and will practically eat anything humans do, but excess feeding will develop risks of illness. Ideally, you should feed them an amount which they can eat up in five to ten minutes every three to four hours. There are also different types of feed for different situations such as early spring, low water temperature, normal feeding, and feed for color enhancing in high water temperature.

Water Quality Control

In Nishikigoi breeding, “filtration” and “purification” are essential steps in water quality control. “Filtration” cleans physical objects such as excretory substances, left-over feed, and leaves, where “purification” eliminates invisible waste dissolved by bacteria and produces clear water. A lauter tub with filtration and purification functions needs to be installed for water control so the Nishikigoi can live in a pleasant environment.

Nishikigoi need sufficient oxygen, so the amount of dissolved oxygen needs to be controlled with an air pump. Lack of oxygen is fatal to Nishikigoi; when they start sticking their noses out of the water or gathering around the water filler, the water needs to be checked right away.

Health Control

Nishikigoi requires daily health monitoring. A group of healthy Nishikigoi swims freely and spreads all over the pond or aquarium and come rushing when it is feeding time. Nishikigoi with signs of diseases gather in one place and hardly move. When Nishikigoi open and close their mouths at the water surface or if you see them gathering around the water filler, the amount of dissolved oxygen is lacking.

In the case of each Nishikigoi, unusually fast-paced swimming, wobbly movements, or motionless behavior at the water surface can be signs of an illness.

Long-awaited arrival of your Nishikigoi!

Placing your Nishikigoi in your pond or aquarium

The Nishikigoi just delivered to your home needs to be well taken care of so it won’t be stressed. Placing it in a new pond or aquarium will cause major changes, so you would need to pay very close attention.

Steps for pond raising:

  1. Do not open the plastic bag right away. Leave the Nishikigoi in the bag for about 20 minutes.
  2. Fill the bag half-full with some pond water to adjust the Koi to the new water.
  3. Then place the Nishikigoi in the pond.

Steps for aquarium raising:

  1. Place the Nishikigoi, water from the plastic bag from the aquarium (1:1) in a tub.
  2. Repeat this several times so the water temperature in the tub equals that of the aquarium.
  3. Then place the Nishikigoi in the aquarium.

Keys to Nishikigoi appreciation

Nishikigoi appreciation consists of three major points. A high quality Nishikigoi is simply beautiful, but at Koi shows where a large number of Nishikigoi are gathered, they are judged on body conformation, quality, and pattern.

  • Body conformation

    This refers to the size and shape of the Nishikigoi. An ideal body is full and has a rounded spindle-like shape.

  • Quality

    This refers to the Nishikigoi’s skin. For example, a Kohaku should have a “snowy” white and vivid hi patterns.

  • Pattern

    The patterns on a Nishikigoi are what make them attractive. A dynamic pattern that catches the public’s eye or a well-balanced pattern brings out the uniqueness in each Nishikigoi.

Related topics

Introduction to Nishikigoi
Koi Varieties