With the appearance of miniature koi, shubunkin goldfish look like delicate exotic fish. In fact, they are nearly as hardy as aquarium goldfish. This is a large breed that needs plenty of space. With a large enough tank, at least 38 litres (10 gallons) of space for each fish, and the right conditions, this variety should do well in a home aquarium. They also thrive in ponds. Shubunkin goldfish thrive in ponds and live for 15 years or longer, so consider your future plans before deciding on them as pets. Goldfish are a long-term commitment.
Prepare a freshwater aquarium with 3.8 litres (1 gallon) of water per 2,5 cm (1 inch) of fish, or a pond with 0.09 square metres (1 square foot) of surface area for each 2.5 cm (1 inch) of fish. Base your measurements on adult fish, not the juveniles you see for sale. Adult shubunkins grow to 25 cm (10 inches), sometimes more; therefore, the smallest possible habitat for this breed would be a 38 litre (10 gallon) tank, which could hold one fish. More realistic is a 7.6 litre (20 gallon) tank for a pair. Include a filter and plenty of aquatic plants in the tank or pond. Goldfish do best at temperatures between about 21.1 and 23.9 degrees Celsius (70 and 75 degrees Fahrenheit). Extra heating is not necessary in temperate climates or if the tank is in a warm room.
Feed the fish goldfish pellets 3 times a day. Goldfish need small, frequent meals. Do not feed the fish more pellets than they can eat in five-minute intervals.
Supplement the pellets with live foods, such as bloodworms, a couple of times a week, especially for goldfish in a tank. Live foods supply extra protein and nutrients and encourage natural behaviour.
Remove 25 per cent of the tank water using the gravel cleaner and bucket, or a smaller proportion of the pond water once a week. Replace with fresh, dechlorinated water. Otherwise, waste build-up leads to toxic levels of pollutants, such as nitrates and ammonia.
Test weekly, at most biweekly, for nitrates and ammonia. Levels of both should be close to zero. If nitrate levels climb above about 25 parts per million or ammonia levels register on the test, change the water in larger quantities or more frequently. Alkaline and acidity levels are optimal at a pH of 6.8 to 7.2.
Dechlorinate tap water by leaving it in buckets for 24 hours. Alternatively, use a commercial dechlorinator from an aquarium supply store. Note that neither method removes chloramine; if your water supply contains this chemical, ask an aquarium supplier for the appropriate treatment.