Freshwater Fish

Goldfish Watonai – Beautiful variety of goldfish

Goldfish are a very popular choice for novice and experienced aquarists alike, but sometimes you want something really special. One of the rarest varieties was recently resurrected, and now you can find the beautiful Watonai Goldfish for sale from specialist breeders. Should you consider this magnificent fish for your aquarium?

What is a Watonai goldfish and why are they special?

The Watonai (pronounced wa-town-eye) is a unique and extremely rare variety of double-tailed fancy goldfish. Originally described in 1908 by Dr. Shinnosuke Matsubara, these Japanese-bred fish were thought to have originally been created from a cross of a Humpback Ryukin and a Fantail Wakin goldfish.

The resulting offspring and their offspring shared traits with both parental lines, most notably having an extremely long double tail and a thick, cold-tolerant build. Unfortunately, this variety of ribbontail disappeared by the middle of the century and appears to be extinct.

Some breeders recently decided to resurrect the variety by breeding new lines from fresh Ryukin/Wakin crosses. Modern Watonai are extremely rare and valuable fish, and can cost upwards of several hundred dollars each, assuming you can find them for sale.

Size and Appearance of the Watonai Goldfish

Watonai is usually about 10 to 12 inches long at maturity, but some pond fish can grow much larger. Wakin’ goldfish can be as long as 19 inches, so it’s certainly possible for one to reach 15 to 19 inches.

What makes the Watonai such a desirable pet? They are bred for their magnificent elongated tail fins (tails) that resemble a butterfly. when viewed from above:

  • They generally have the longer, more streamlined body shape of the Wakin, along with a dorsal fin (unlike the Ryukin).
  • Their fins spread widely behind them as they swim, and their elegant double-ribbed tails are at least as long as their bodies.
  • This variety is the most elegant type of goldfish that is suitable for life in a pond.

Life expectancy

Since the modern Watonai is such a new lineage, we don’t really have hard factual information on its average lifespan. Other types of goldfish can live 20 to 40 years when properly cared for, so there’s no reason to think this variety can’t reach such a venerable age.

behavior and temperament

Goldfish are peaceful and social fish that are generally active and curious about their surroundings:

  • Watonai have classic goldfish personalities and enjoy swimming and foraging for food.
  • Their bodies are not as streamlined as the Wakin, so they tend to be slower swimmers, but they can navigate well in an aquarium or pond.
  • They can uproot live plants and litter your aquarium, but are less likely to cause any real destruction to your plants, unlike the common variety, which often playfully kills them.

How to take care of your Watonai goldfish

Watonai care requirements are similar to other types of fancy goldfish, so you don’t need to worry about mastering any special skills to have a healthy group of fish.

ideal aquarium size

You will need at least a 30 gallon tank for a single Watonai, and you need to add an additional 15 to 20 gallons per fish to give them all the right space. With their elaborate and widely spread tails, they do best in longer and wider tanks.


To avoid any injury to their long ribbon tails, it is best to use a soft sand type of substrate or smooth rounded pebbles over rough aquarium gravel. These fish look particularly magnificent when viewed against a dark colored substrate or background.

temperature and water conditions

Unlike many fancy goldfish varieties, the Watonai is a hardy type and does well in temperatures from 60 to 78°F. However, you’ll want to maintain a consistent temperature, so you may need to use a heater in the colder months. They are not particularly sensitive to water hardness, and do well from pH 6.0 to 8.0.

Filtration, aeration and lighting

The Watonai has identical requirements to other varieties of goldfish when it comes to their filtration preferences. They are sensitive to ammonia and other aquatic waste products, so a good filtration system with replaceable filter media is a must.

They actively avoid swimming in currents. , so smooth flow is preferred (using baffles if necessary). While they are tolerant of low oxygen conditions, it is best to make sure your tank has good, smooth circulation. A well-placed air stone can help. 8 to 12 hours of light a day is adequate for these goldfish.

Plants and Decorations

While it’s not always a good idea to mix goldfish and live plants, your Watonai may be fine with them, as they don’t tend to be as destructive as single-tailed varieties. When choosing plastic plants and decorations, be sure to opt for rounded products and avoid those with sharp edges that could catch or injure their long tails.


If you want your Watonai to display its most impressive colors but avoid obesity and health complications, it’s best to feed it once a day. I also fast my adult fish one day a week to mimic their natural feeding behavior.

  • Feed them a high-quality commercial goldfish diet , giving them as much as they can consume in a few minutes.
  • Offer sweet foods, such as brine shrimp or bloodworms, instead of their usual meal once or twice a week, or more often if preparing for spawning season.

tank mates

The best tank mates for goldfish are other goldfish or koi of a similar size, and you could easily raise a mixed tank of fancy fish alongside your Watonai. Avoid keeping them with aggressive species or small animals that can swallow. Here is a list of suitable goldfish companions.

Brief look at the breeding of Watonai

Breeding goldfish is not as easy as betta fish and live carriers, so you’ll need to research the various methods and set up your breeding and fry tanks well in advance. Some important considerations include:

  • Spawning is induced by changes in temperature. , so you’ll need to lower it in your breeding tank for a few weeks and then gradually increase the temperature a couple of degrees a day until it’s around 74 to 78°F.
    • Your females will become especially round and plump as they prepare to lay their eggs.
    • Male goldfish develop white, pimple-like bumps on their gill covers and fins when they are ready to fertilize the eggs.
  • Using a spawning mop makes it easy to transfer the delicate eggs to your fry tank, but you can also use live plants like Hornwort and transfer the adults to another tank after they spawn.
    • the adult goldfish will eat the newly hatched fry, so it is best to separate them before they hatch.

Maintenance and health concerns

Watonai, like all goldfish, get very stressed when their water is dirty or not changed on a regular schedule, and high levels of ammonia or nitrate can lower their immune systems and make them susceptible to opportunistic diseases. You must be diligent in maintaining your goldfish tank and its filtration equipment.

Elegant goldfish like watonai are prone to problems with their swim bladders, so avoiding obesity is a key way to maintain good health. in your fish Their long fins are easily injured and prone to infection. It is better to prevent disease outbreaks than to have to treat them.

Ultimate Watonai Tank: List of equipment and supplies

Once you’re ready to take the next step and set up a tank for Watonai, you’ll need a list of necessary equipment. For a tank suitable for 3 of these elegant goldfish, you will need:

  • 60 to 75 gallon (or larger) aquarium and pedestal, preferably a custom or long style tank with a clear cover
  • Lamp
  • HOB or canister filtration system
  • Sandy or smooth pebble-based substrate
  • Live plants or smooth plastic versions and other safe decoration with no sharp or rough edges
  • A bottle of water conditioner.

To feed your Watonai, you will need:

  • Commercial goldfish flakes or pellets
  • Try foods like brine shrimp, bloodworms, or mosquito larvae.

Optional equipment that you may find useful includes:

  • an aquarium heater
  • An air pump and an air stone.
  • Baffles for your filtration system
  • A UV sterilizer
Common name (species) Watonai goldfish (carassius auratus)
Family Cyprinids
Source Japan; however, the original line has died out. Modern Watonai are descended from recent Ryukin and Wakin goldfish crosses, and are not related to the original lineage.
Diet and feeding Omnivore; Commercial goldfish diets are ideal, supplemented with live/frozen/dried treats such as brine shrimp, bloodworms, Daphnia eggs, and mosquito larvae.
level of care easy to moderate
Exercise Social, active and curious
Temper Peaceful, sometimes bites other fish.
size range Juveniles are typically sold 2 to 4 inches long.

Adults generally average 10 to 12 inches at maturity, but some Watonai ponds can potentially reach up to 19 inches.

tank level Uses all levels, but prefers lots of open swimming areas.
Minimum tank size 30 gallons; Longer, wider tanks are preferred over tall, narrow designs. Add 15 to 20 gallons per adult goldfish.
Temperature range 60 to 78°F
Hardness of water 0-25KH It works well in a wide range of conditions as long as they are stable.
pH range 6.0 to 8.0
Filtration / Flow Rate It prefers well-filtered, very clean water with minimal current. Strong currents can potentially damage their delicate tail fins and they will avoid areas with too high a flow.
Breeding Egg layer; They breed naturally in the spring as the temperature in their enclosure rises after a cooler period.
Compatibility It is well suited to aquariums or ponds with other varieties of goldfish or koi and fish that are too large to be eaten; Avoid housing with aggressive or semi-aggressive species or fish that may pinch your elaborate fins.
Is this ok for planted tanks or ponds? Yes, a good option for planted tanks and a great option for ponds as long as there is enough room for the fish to swim. However, some goldfish may uproot your plants for fun.


If you’re ready to invest in one of the most impressive types of fancy goldfish, you can’t do better than choose the Watonai. They are not particularly difficult to care for and their sturdy build makes them an ideal choice for aquariums and ponds. We’d love to hear all about your fancy goldfish, so leave a note in the comments below!

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