The Showa koi reads as a black fish wearing red and white, not a white fish with markings added. Its black wraps around the belly. It is a pond fish that stays near the bottom, and keeping one takes a little experience.
Did you know
The Showa koi is the youngest of the big three, shown thirteen years after Sanke and decades after the founding Kohaku spawning. A modern kindai Showa can carry so much white that it passes for a Sanke. The black in the pectoral fin joints settles the argument.
Caring for the Showa koi
Showa koi need a pond, because koi are not aquarium fish. One fish needs at least 264 gal (1,000 L) to start, and a group needs a pond of several thousand liters. Run strong filtration, because koi are big, messy eaters.
They cope with a very wide temperature swing, from 39 to 81°F (4 to 27°C), at a pH of 7.0 to 8.5. Koi stay active in summer warmth and slow nearly to dormancy under winter ice. Stable, well oxygenated, well filtered water matters far more than any narrow target.
Feed a varied omnivore diet of sinking koi pellets and greens, with occasional live or frozen foods. Showa koi are peaceful and social, and they do fine alone or in a group. They mix with goldfish and other large, peaceful pond fish, but they uproot plants and eat anything small enough to swallow. Breeding koi is a moderate challenge.
The black, called sumi, keeps moving for years, so a Showa bought at six inches rarely looks the same at two feet. Shops carry both the heavy black traditional type and the white heavy kindai type. Ask which one you are being sold.
Good to know
The Showa was built by crossing Kohaku into the black and yellow Ki Utsuri. Its black therefore behaves like Utsuri sumi, forming a base layer rather than spots sitting on white. That is why sumi crosses the head, often as a wedge or lightning stripe, and gathers at the pectoral fin joints as motoguro. Yellow carried in from the Ki Utsuri side is the usual explanation for the muddy color of early Showa. Its full name, Showa Sanshoku, comes from the Showa era it appeared in.
In the wild
The Showa koi was first exhibited in Japan in 1927. Accounts credit a Niigata breeder named Hoshino, though they disagree on his given name. It stayed a curiosity for a long stretch. Hobby histories credit Kohaku blood introduced by Tomiji Kobayashi in the 1960s for the clean reds and whites seen now.
Common questions
Is a Showa koi a different species from the koi?
No. A Showa koi is a variety of the koi, Cyprinus rubrofuscus, and it wants the same tank, water and food as the species.
What size tank does a Showa koi need?
A Showa koi needs at least 264 gal (1,000 L). It spends most of its time in the bottom.
What does a Showa koi eat?
A Showa koi eats a varied omnivore diet of sinking koi pellets and greens. Occasional live or frozen foods add variety.
11.8 in (30 cm)119 gal (450 L)39–75°F (4–24°C)
23.6 in (60 cm)317 gal (1,200 L)72–82°F (22–28°C)
6.3 in (16 cm)37 gal (140 L)68–79°F (20–26°C)
5.9 in (15 cm)63 gal (240 L)68–81°F (20–27°C)
4.7 in (12 cm)63 gal (240 L)57–68°F (14–20°C)
23.6 in (60 cm)660 gal (2,500 L)68–79°F (20–26°C)