How to keep Nishikigoi

Keeping koi indoors

Aquariums filled with colourful ornamental fish have become fully integrated into stylish interior design. With well-designed tanks and various breeding equipment, keeping ornamental fish has become much easier and more enjoyable. Nishikigoi, which has a long history as the king of ornamental fish, is now attracting attention as a new star in the aquarium layout.

Items to prepare

  • Tank
  • Glass cover
  • Filter (filtration device)
  • Lighting fixture
  • Air pump
  • Air stone
  • Water thermometer
  • Gravel
  • Heater
  • Thermostat
  • Chlorine neutralizer
  • Net
  • Koi food

Setting up the fish tank

  1. Choose the placement location. Filling a 60cm tank with water will weigh approximately the same as one adult male.
  2. Set up the filter, thermostat, heater, and other equipment. While Nishikigoi can be kept at room temperature throughout the year, it is advisable to use a heater and thermostat for insulation during the winter months.　The gravel should be washed thoroughly before use.
  3. Add water. Use tap water after neutralizing the chlorine. After adding water, activate the filter and circulate the water for 2 to 3 days before introducing the Nishikigo. This is for their safety.
  4. Introduce the koi. Before opening the bag, immerse it in the tank to equalize the water temperature, then carefully transfer only the koi into the tank.
  5. When the aquarium has just been set up, feed the fish sparingly.

Routine care

  1. Feed once or twice a day, giving an amount the fish will consume within a few minutes.
  2. When changing water, replace approximately one-third of the water.
  3. Depending on the water contamination, the filter media should be removed to a separate container and rinsed in either water from the tank or dechlorinated water. Do not use detergent.
  4. When the water level drops, replenish with fresh water.

Source: “Invitation to Nishikigoi” All Japan Nishikigoi Promotion Association (planning)

Keeping koi on the balcony

You can enjoy keeping koi on the balcony with simple ponds or medium to large-sized tanks. Product development for Nishikigoi has been actively pursued, making them simple and easy to care for.
Keeping koi in apartments or condominiums is becoming increasingly popular year by year.

Items to prepare

  • Fish tanks (made of FRP, etc.)
  • Filtration system (Since the water volume increases compared to glass tanks, it is necessary to prepare one with filtration capacity suitable for the water volume)
  • Air pump
  • Air stone
  • Water thermometer
  • Net
  • Chlorine neutralizer
  • Koi food
  • Sunshade

Setting up the fish tank

  1. Choose a location for installation. Place it horizontally in a convenient location for drainage.
  2. Add water. Neutralize tap water with the specified amount of chlorine neutralizer.
  3. Operate the equipment. Activate the filtration system to check the water environment.
  4. Introduce the koi. After setting up, circulate the water for about a week before introducing the koi. Float the bag containing the koi in the tank to adjust the water temperature before carefully adding them.

Routine care

  1. Feed two to three times a day, giving an amount the fish will consume within a few minutes.
  2. If direct sunlight enters and causes the water temperature to rise too much, place a sunshade.
  3. Check the filtration system periodically. If clogging occurs, remove the filter media to a separate container and wash it using water from the tank. Do not use detergent.
  4. Replenish with fresh water if the water level drops due to evaporation or other causes.
  5. Regular small water changes are recommended, but if the water becomes heavily soiled, it is advisable to replace approximately one-third of it.

Source: “Invitation to Nishikigoi” All Japan Nishikigoi Promotion Association (planning)

Keeping koi outdoors

Outdoor ponds are the perfect environment to appreciate the majestic presence of gracefully swimming koi. Some may believe koi are best kept in ponds with river water, but the most suitable environment is a pond equipped with a circulation filtration system. Due to advancements in filtration systems, koi keeping has become accessible in a wide range of ponds, from traditional Japanese-style ones to contemporary dedicated keeping tanks. Furthermore, koi can be kept in various environments, including ponds constructed on the rooftops of buildings and makeshift ponds made with waterproof sheets.

Items to prepare

  • Keeping pond
  • Filtration system (filter tank, cleaner, etc.)
  • Net
  • Koi food

Routine care

  1. Prevent garbage, dead leaves, and rainwater from gutters from entering the pond.
  2. The debris settled at the bottom of the pond should be drained using a pump or similar equipment. Designing the pond with a bottom drainage system in advance is convenient. Ponds with a circulation filtration system, including filter tanks, require fewer cleaning sessions.
  3. Do not overfeed. Reduce feeding when the water temperature is low (below 8°C).
  4. Inspect the water condition and wash the filter media with pond water every 2 to 3 months.

Effective Care and Planning for Koi

The basic requirements for keeping koi are a tank or pond and a filtration system. Depending on the location and conditions, these combinations can fit various setups, so it’s best to consult with nearby stores or specialists first. When keeping koi fish, it’s important to avoid
overfeeding, overcrowding, excessive water changes, and over-cleaning the filtration system. Shops will provide tanks, ponds, filtration systems, and other equipment to accommodate your desired setup for keeping koi. Initially, consulting with a shop is optimal to ensure that keeping and appreciating koi is straightforward, enjoyable, and enduring.

Source: “Invitation to Nishikigoi” All Japan Nishikigoi Promotion Association (planning)