Tosakin Goldfish; Care Guide, Lifespan, and More

The Tosakin goldfish is an extremely rare variety of the popular Fantail goldfish.

Tosakins have an incredible history that you’ll learn more about later in this guide. However, from the get-go, you need to know that these goldfish are hard to find, expensive to buy, and terribly delicate. We don’t recommend the Tosakin as a good goldfish for beginners for those reasons.

Read this guide to learn more about the fascinating Tosakin, including how to care for them.

Origins Of The Tosakin Goldfish

All modern goldfish breeds originate from a species of wild Prussian carp that was kept and raised in ponds as a food fish.

Carassius auratus were first bred in the early 1700s in China. One day, a fishkeeper spotted a few brightly colored orange carp mixed with the drab, gray ones. Instead of consigning the fish to the pot, the fishkeeper removed those “goldfish” and kept them as decorative pets.

Over many years, many different shapes, colors, and patterns of goldfish were developed by enthusiastic breeders, and by the 1800s, the fish were being traded across Asia, Europe, and the US as ornamental pond fish.

What is a Tosakin Goldfish?

Very few people have heard of the Tosakin goldfish. In fact, hardly anyone keeps or breeds these fish outside of Japan, where the variety originates.

The fish are characterized by their flamboyant, undivided tails that fan out, extending from gill to gill when viewed from above. The first Tosakin goldfish was recorded in Japan in 1845 in Tosa, now known as the Kochi Prefecture, becoming established in the Meiji period from 1868 to 1912.

Extinction Event!

The beautiful Tosakin was almost lost forever, thanks to a sequence of events that took place in the mid-1900s.

Following the heavy bombing of the region in World War II, an earthquake and tsunami devastated the area, causing many people to believe that the Tosakin had gone extinct. But Mr. Hiroe Tamura, a Japanese breeder, found six of the fish in a restaurant. With cash in the country now worthless, Mr. Tamura traded a bottle of sweet potato vodka for the Tosakins!

Two of the fish were a breeding pair, and the remainder were around four years old. That discovery saved the breed, leading to the Japanese government declaring the Tosakins a National treasure of the Kochi Prefecture. Today, the fish are also known as Peacock Tail, Curly Tail, or Queen of the Goldfish in Japan, with Ranchus being the King.

Incredibly, it’s thought that all the world’s surviving Tosakin goldfish are descended from those WW2 survivors! It’s also claimed by some enthusiasts that the Tosakin was originally created by breeding a Ryukin with an Osaka Ranchu, another incredibly rare breed that’s thought to be almost extinct.

Tosakin Goldfish Lifespan

Tosakin goldfish are fragile, inbred creatures that have a relatively short lifespan of around ten years.

Tosakin Goldfish Appearance

Rather like the Butterfly goldfish varieties, Tosakin goldfish are bred to be viewed from above, an aspect that best shows off the fish’s amazing, circular tail.

These goldfish have a full dorsal fin and the other fins are also classed as intact. The exception to that is the tail, which is sometimes described as a cherry blossom or triple lobe tail. The tail’s inner edges are webbed, while the outer lobes are twisted toward the head and upturned, giving the impression that the tail has been inverted.

What Size Are Tosakin Goldfish?

Tosakin goldfish can grow to around 6 inches in length.

Colors And Patterns

Compared with other species of goldfish, the Tosakin has a somewhat limited range of colors and patterns to offer the collector, including:

  • Iron black
  • Red
  • Red-and-white
  • Calico

Any Tosakin that emerge with silver-white or yellow coloration on their caudal fins are immediately designated National treasures.

Price And Availability

As previously mentioned, Tosakin goldfish are extremely hard to find, so it’s highly unlikely that you’ll find one of these beautiful fish in your local fish store. 

However, you can sometimes find Tosakins for sale online, starting at around $60 for a standard red-and-white example. Rarer colors will command a much higher price than that. 

Is The Tosakin Goldfish Suitable For Beginners?

Tosakin goldfish are incredibly fragile fish that are prone to many health problems, largely caused by too much inbreeding.

For that reason, we don’t recommend this goldfish variety for beginners.

Tosakin Goldfish Care Guide

In this part of our guide, you can learn how to care for the enigmatic Tosakin goldfish.

Tank Size

There is much debate about the tank size and shape that’s required for Tosakin goldfish. However, we recommend that you choose an aquarium of at least 10 gallons. For each additional fish, add a further 10 gallons.

Like most round-bodied Fancy goldfish, the Tosakin is an appallingly lousy swimmer, wobbling around the aquarium in an ungainly swimming style. The fish is hampered by its massive tail fin, to make matters worse. So, choose a long, shallow tank rather than a deep one to make it easier for the Tosakins to swim to the surface to feed.

A rectangular tank also provides more surface area for better gaseous exchange, essential for these oxygen-hungry fish.

Technically, Tosakins could live outside in a garden pond. However, these are valuable, delicate fish probably best cared for in an aquarium.

How Many Fancy Goldfish Can You Keep?

Overcrowding is a major cause of disease outbreaks in fish. So, although your Tosakins will enjoy the company of other Fancies, you should avoid overcrowding them.

Ideally, you should allow 1 inch of fish to 1 gallon of water in your fish tank.

Water Parameters

Tosakin goldfish need a water temperature of between 65o and 72o Fahrenheit. The water pH must be between 6.0 to 8.0, with a water hardness of between 5 and 19 dGH.

Ammonia and nitrite levels must be zero, with nitrates around 20ppm or less. 


All goldfish are very dirty fish that produce lots of waste, polluting the water in the tank. So, you’ll need to run an efficient filter system.

Your filtration system needs to move the water in your tank through the filter media at least four times every hour. Your filter needs both mechanical and biological media to keep the water clean and safe for your Tosakins.

However, like all round-bodied goldfish, Tosakins are not very good swimmers, and they don’t appreciate a strong current in their tank. So, you need to either buffer the water flow with solid decorations or plants or choose a filter system with an adjustable outflow valve.  

Tank Maintenance

The filter system takes some basic maintenance to keep it running efficiently. Once a month or so, rinse the filter media in tank water to remove sludge and keep the water flowing through the filter media. You’ll also need to replace spent media in line with the manufacturer’s instructions.

Every week, you need to change around 30% of the water in the tank to remove nitrates. Use an aquarium vacuum to remove accumulations of organic waste from around plant bases and underneath filter boxes and decorations. 

Trim off dead or brown plant leaves and broken stems, and remove algae from the aquarium glass. Goldfish do eat algae as part of their regular diet, so we recommend that you leave a small patch of algae somewhere out of sight for the fish to graze on during the day.

Tank Decoration

Tosakin goldfish don’t need any special tank decorations, but there are a few things to consider when aquascaping your tank.

Safety First!

Tosakin goldfish can be vulnerable to tail injuries. So, you should avoid putting anything sharp in the tank, such as twisted roots that could snag your fishes’ tails.

These fish are poor swimmers, too, so we recommend that you put decor items around the tank’s perimeter, leaving plenty of open swimming areas in the middle of the aquarium. Suitable items of decor can include smooth stones, driftwood, and pebbles.

Goldfish enjoy rooting around in the substrate for scraps of food, and large, smooth gravel is the best choice for a goldfish tank.


Living plants can bring many benefits to a goldfish tank. Plants take up CO2 and give off oxygen. Live plants also use harmful nitrates as fertilizers, helping to keep the water clean and well-oxygenated for the fish.

Unfortunately, goldfish are renowned diggers, and they can sometimes uproot plants; and as omnivores, Tosakins will nibble on tender new plant shoots. However, if you choose tougher plants like Marimo Moss Balls, Java ferns, and Anubias, they should survive in a goldfish tank.


Live plants need at least eight hours of light each day for photosynthesis.

Fish also appreciate a day/night lighting pattern. The morning light tells the fish that it’s time to eat and become active, while the darkening of the tank in the evening lets the fish know that it’s time to sleep. It’s thought that a clear day/night pattern helps to prevent the fish from becoming stressed.

If you’re not around to turn your tank lights on and off manually, invest in a lighting unit with an integrated timer or buy a cheap plug-in timer that you’ll get from a DIY store. 

Nutrition and Feeding

Tosakin goldfish are omnivores, eating a diet of plants, algae, and meaty protein. So, a good basic diet for your goldfish could include:

  • High-quality Fancy goldfish flakes and pellet food
  • Frozen meaty foods, such as brine shrimp and bloodworms
  • Blanched fresh vegetables, such as peas, zucchini, and spinach

All round-bodied goldfish are prone to digestive issues, especially constipation and bloating. Dried food accumulates in the fish’s gut, eventually causing a blockage and displacing the swim bladder. That prevents the fish from swimming on an even keel and affects buoyancy and balance. Sometimes, affected fish might struggle to get off the substrate or become trapped at the surface, unable to swim down again. That’s highly stressful for your fish, potentially leading to feeding problems and health issues.

You can prevent swim bladder issues by including a portion of meaty protein or fresh vegetables in your fish’s daily diet.

How Much To Feed?

Tosakin goldfish should be fed two or three times each day. Give your fish small amounts of food that they can eat within a few minutes to avoid overfeeding.

What Are Good Tank Mates For Tosakin Goldfish?

Tosakins are very peaceful fish that benefit from the company of other Fancy goldfish. You might also want to consider including large species of shrimp and snails in your goldfish community.

 We recommend that you avoid mixing slim-bodied goldfish types, such as Comets, as they can cause problems at feeding times by hassling or bumping into the slower Tosakins. Very small shrimp should also be avoided, as your goldfish will probably eat them! 

Health and Diseases

As well as digestive issues, Tosakins are prone to line-breeding-related issues. Unfortunately, the intensive in-breeding program that was used to try to resurrect and save the species from those original six surviving fish has caused some congenital health problems.

Tail Curling

Tail curling is a problem that only affects Tosakins. Basically, the caudal fin becomes overdeveloped so that it protrudes all the way along the fish’s body, actually becoming stuck in the gills when the fish is resting.


Ich is also commonly known as White Spot Disease or Ick.

White Spot is caused by an aquatic parasite that’s often found in freshwater and saltwater aquariums. The parasite generally only attacks fish that are already under stress or are diseased. Infected fish flick or flash against solid objects in the tank. Within a few days, a rash of tiny white spots like grains of salt develops on the fish’s gills, fins, and body.

Provided it’s treated early, you can successfully treat White Spot with an over-the-counter medication that you’ll get from pet stores.

Bacterial Infections

Secondary bacterial infections usually attack Tosakins that are weak or injured. There are many symptoms of bacterial infections, depending on the species of bacteria involved, but can include: 

  • Reddened skin
  • Ulcers
  • Inactivity
  • Poor appetite
  • Missing scales
  • Labored breathing
  • Ripped or ragged fins

Most simple bacterial infections respond well to medication that you can buy in pet stores or your veterinary clinic.


Flukes are external parasites that can attack freshwater fish. The most common species of flukes include:

  • Anchor worms
  • Fish lice
  • Skin flukes

Flukes usually get into your aquarium on new livestock, among plant leaves, or with live food. You can keep flukes out of your tank by quarantining new arrivals for a couple of weeks before introducing them to your main setup.

Breeding Tosakin Goldfish

Tosakin goldfish are rare creatures that are already very interbred. 

Professional breeders have the knowledge of fish genetics and breeding techniques that are necessary to prevent congenital health problems from affecting their breeding stock. For that reason, we don’t recommend that you try to breed these fish at home. 

Final Thoughts

Tosakin goldfish are a rare and unusual species of goldfish that are seldom seen in fish shops. These delicate fish can be weaker than regular Fancy goldfish, so we don’t recommend them for beginners.

If you decide to take on Tosakin goldfish, you’ll need to provide a large tank of at least 10 gallons with an efficient filter system that can cope with the huge quantity of waste that goldfish produce. You can keep Tosakins with a group of peaceful, round-bodied Fancy goldfish, some large shrimp species, and a few snails to create an interesting display. Live plants are a good addition to the aquascape, but avoid using sharp or rough objects that could snag the fishes’ huge round tails and cause injury.

Do you keep Tosakin goldfish? Where did you find them for sale? Tell us about your fish in the comments box below!

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