Tosakin

Looks how to spot one

Scaled fish with metallic scales, a ryukin-type body and a huge, flat, curled-edge twin tail

A rounded, ryukin-type goldfish whose glory is its tail. The broad tail is joined in the middle and spreads out flat and sideways like an open fan, with its outer edges curling forward and under once or twice. Because of this, tosakin are traditionally admired from above rather than from the side.1256

Personality what they are like

Calm and graceful, with a slow, unhurried swimming style. Despite its delicate look it is as hardy as most deep-bodied fancy goldfish.1

Daily activity how busy a day looks

Low. A slow swimmer that prefers calm water; gentle sponge filtration is recommended over strong currents.12

Grooming and care the hands-on bits

Use gentle filtration such as a sponge filter and avoid strong water movement. Keep water clean with regular partial water changes using dechlorinated water at the same temperature; general goldfish guidance gives about 10 to 21 C and pH 6 to 8.1738

Home where they are happiest

Young tosakin are traditionally raised in shallow, round, bowl-shaped containers so they swim along the curved edge and their tails grow in the correct shape during the first year. Adults are usually kept in shallow, wide containers that are viewed from above.12

Food basics what goes in the bowl

Omnivores. Offer a goldfish-specific pellet as the staple, which suits their need for less protein and more carbohydrate than many fish foods. Add chopped vegetables such as peas or spinach and small amounts of daphnia or brine shrimp as treats. Feed two or three small meals a day, giving only what is eaten within two to five minutes.93

Company who they like around

Peaceful. Best kept with other tosakin or very calm fancy goldfish rather than in a busy mixed tank.210

The story where it all began

The tosakin was developed in the Tosa domain, probably by a lower-ranking samurai who crossed ryukin with Osaka ranchu. War damage and a 1946 earthquake left only a handful of fish, until hobbyist Hiroe Tamura found six survivors at a local restaurant and rebuilt the breed. It was declared a natural monument in 1969 and reached Tokyo hobbyists around 1971.12

Recognised by the official bits

Kochi Prefecture / Japan

Designated a natural monument (Wikipedia: 'Natural Treasure', 1969)1

Japanese goldfish fancy

Counted among Japan's three great regional goldfish, with the jikin and the Izumo nankin2

Goldfish Society of Great Britain (GSGB)

Listed as a standard variety, noted for its unique tail with greatly extended lower lobes and up-turned outer edges6