Tancho Kohaku Koi

Tancho Kohaku Koi — a pristine white body crowned with a single crimson circle. The rarest and most revered pattern in Japanese koi keeping.

• Water Conditions: Tancho Kohaku Koi thrive in well-oxygenated, clean water with a temperature range of 59°F–77°F (15°C–25°C). They are cold-water fish that can tolerate temperatures as low as 39°F (4°C) during winter dormancy, but they become stressed above 82°F (28°C) when dissolved oxygen levels drop. Maintain a pH between 7.0 and 8.5, with a stable carbonate hardness (KH) of 80–120 ppm to buffer against pH swings. Ammonia and nitrite levels must always read 0 ppm, and nitrate should remain below 40 ppm. These koi produce significant biological waste, so a robust filtration system — ideally a combination of mechanical, biological, and UV clarification — is essential. Perform weekly water changes of 10–20% to maintain water clarity and reduce toxin buildup. Never introduce koi into a newly cycled pond; the nitrogen cycle must be fully established before stocking.
• Pond & Space Requirements: Although this listing shows a juvenile size range, Tancho Kohaku Koi are true pond fish that will grow rapidly to 24–36 inches (60–90 cm) in adulthood. A single koi requires at least 250 gallons of water, and for a group of 4–6 fish, you should plan for a pond of at least 1,000–1,500 gallons. Depth should be a minimum of 3 feet (90 cm) to provide thermal stability and protection from predators. The pond should receive partial shade to prevent excessive algae growth, but also enough sunlight to promote healthy colour development — particularly the vibrant red of the Tancho marking. A bottom drain and skimmer are strongly recommended for efficient waste removal.
• Tank Mates: Tancho Kohaku Koi are peaceful, social fish that thrive in the company of other koi varieties. Ideal tank mates include other koi breeds such as Showa, Sanke, and Shiro Utsuri, as well as goldfish varieties like Sarasa Comets and Wakin. Because koi are omnivorous and will eat anything that fits in their mouths, avoid small fish such as minnows, guppies, or juvenile goldfish under 3 inches. In a pond environment, they coexist beautifully with weather loaches, which help aerate the substrate, and with koi-safe aquatic snails that consume algae without harming the fish. Avoid aggressive fish like large cichlids, Oscar fish, or any species that may nip at the koi's fins. Also, be wary of keeping them with turtles, as turtles can damage the koi's skin and body. When mixing koi sizes, ensure all fish are similar in length to prevent larger specimens from bullying or outcompeting smaller ones for food.
• Feeding Habits: Tancho Kohaku Koi are omnivorous and remarkably enthusiastic eaters, often rushing to the surface when they see their keeper approach. Feed a high-quality, sinking or floating koi pellet with a protein content of 30–36% during the active growing season (water temperatures above 59°F/15°C). Offer a variety of supplementary foods such as spirulina flakes, freeze-dried brine shrimp, bloodworms, and blanched vegetables like lettuce, zucchini, and peas to enhance colour and immune health. Feed small amounts 2–3 times per day, offering only what they can consume within 2–3 minutes per feeding to avoid overfeeding, which pollutes the water and stresses the fish. As temperatures drop below 50°F (10°C) in autumn, reduce feeding frequency to once per day with a wheat-germ based, low-protein diet. Below 46°F (8°C), stop feeding entirely, as their metabolism slows to near-dormancy and undigested food can rot inside their gut, causing fatal bacterial infections.
• General Care & Health: The Tancho Kohaku is celebrated for its elegant simplicity, but this pure white body makes it more susceptible to stress-related pigment changes. Consistent water quality is the single most important factor in maintaining the brilliant white "shiroji" and the vivid crimson "tancho" circle. Perform weekly water tests and keep a log of your parameters. Quarantine any new arrivals for 2–4 weeks in a separate tank before introducing them to the main pond to prevent outbreaks of koi herpesvirus (KHV), carp edema virus (CEV), or parasites like costia and trichodina. Watch for signs of distress: flashing (rubbing against surfaces), gasping at the surface, clamped fins, or red streaks on the body. Regularly inspect the gills and skin for ich (white spots), ulcerations, or fungal infections. Supplement their diet with vitamin C and immune-boosting additives during seasonal transitions. Provide a pond net or predator deterrents such as heron statues or motion-activated sprinklers to protect your koi from birds, raccoons, and cats. Clean mechanical filters weekly and backwash biological filters monthly to reduce organic load. With diligent care, a Tancho Kohaku can live 25–35 years and become a treasured centrepiece of your water garden, growing increasingly beautiful with each passing year.
• The Distinctive Tancho Pattern: What sets the Tancho Kohaku apart is its namesake — a single, round red patch on the top of the head, reminiscent of the Japanese flag. The body must be predominantly pure white with no red markings anywhere else, and the patch should ideally be centered between the eyes and the dorsal ridge. Koi with this pattern are considered the rarest and most auspicious in Japan, often commanding premium prices at auction. Be aware that the Tancho marking can shift or fade with age, stress, or water quality changes, so maintaining stable conditions is paramount to preserving this iconic pattern. Some specimens may develop tiny secondary red spots on the body — these are considered a flaw and lower the fish's show quality, though they do not affect health or hardiness.