Showa Koi

Looks how to spot one

scales

Showa have a sturdy, elongated carp body covered in scales. Their most striking feature is the tri-colour pattern: a black (sumi) base overlaid with bold red (hi) and white (shiro) markings. The black often extends onto the pectoral fins, creating 'motoguro' markings that distinguish Showa from the similar Sanke variety.12

Personality what they are like

Showa koi are generally calm, social pond fish that do best in stable outdoor systems with plenty of swimming room. Healthy koi often learn feeding routines and may become comfortable approaching people at the pond edge. Their personality is shaped as much by pond conditions, stocking density and handling stress as by variety.4

Daily activity how busy a day looks

Showa koi are active swimmers that need open swimming lanes, steady circulation and enough depth and volume to move naturally without crowding. A cramped pond can increase stress, aggression around feeding and disease risk. They benefit from environmental variety such as shaded areas, safe plants and consistent water movement.4

Grooming and care the hands-on bits

Preventive care starts with stable water. Routine partial water changes (10% to 25% every two to four weeks), dechlorinated replacement water, debris removal, filter maintenance and regular testing for ammonia, nitrite, nitrate, pH and hardness are the foundation of long-term health. A UV clarifier helps control green water, and a surface skimmer manages leaf litter.34

Home where they are happiest

Showa koi require a minimum pond size of 1000 gallons for healthy adults. The pond should be at least 3 feet deep for cold-climate winterisation. Water temperature should stay between 50 and 78°F (10 to 26°C) seasonally, with pH 7.0-8.5, ammonia and nitrite at 0 ppm, nitrate under 40 ppm and dissolved oxygen above 5 mg/L. Filtration should be sized 1.5-2 times the pond volume per hour. Aeration is non-optional in summer.34

Food basics what goes in the bowl

Showa koi are omnivores. They thrive on high-quality commercial koi pellets, with occasional variety from safe frozen or freeze-dried foods such as mysis or bloodworms. Diets containing spirulina or krill can help enhance red colouration. Feed only what the fish can finish in one to two minutes per feeding, and adjust frequency with water temperature: less when cool, once or twice daily in warmer water.24

Company who they like around

Showa koi are social pond fish that do best in groups. They are generally peaceful and can be kept with other koi varieties. Overcrowding should be avoided as it can lead to stress and aggression, especially around feeding time.4

The story where it all began

The Showa variety was first developed around 1927 by Japanese breeder Jukichi Hoshino, who crossed a Kohaku (white with red markings) with a Ki Utsuri (yellow with black bands). Early Showas had dull, off-colour reds and whites because of the yellow influence. The variety was named after the Showa era (1926-1989), the period of Emperor Hirohito's reign. In 1964, breeder Tomiji Kobayashi crossed a male Kohaku with a female Showa to produce a new style with a large crimson red pattern and a brighter white ground. This 'Kobayashi Showa' line is the basis of most modern Showas. Later, Minoru Mano bred a spectacular 'inazuma' (lightning pattern) Showa that brought major improvements in body shape and colour quality. Showa is one of the Gosanke, the 'Big Three' koi varieties, alongside Kohaku and Sanke. What makes Showa distinct from Sanke is that Showa has a black base with red and white markings, whereas Sanke has a white base with red and black markings. The black on Showa also typically extends onto the pectoral fins (motoguro), which is rare in Sanke.125

Recognised by the official bits

Koi hobbyist community (Gosanke)

Showa is one of the Gosanke, the 'Big Three' koi varieties alongside Kohaku and Sanke.1