Ranchu Goldfish: Ultimate Guide (Care, Diet, Breeding & More)

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Written By Matt Stevens

Hi, I'm Matt! I've been obsessed with fishkeeping for over 15 years now and created this site to share my knowledge with others.

Ranchu Goldfish are a unique Goldfish variety that’s easily recognized by their absent dorsal fin. They are a slow-moving species that are endemic to Japan and China.

Believe it or not. You won’t see a fish so unique yet so charming in many ways. More importantly, you may never find a medium-sized goldfish that’s so beautiful yet so rare at the same time.

And if you think about their dorsal-less configuration, you will want to add a new Ranchu Goldfish to your home aquarium straightaway.

But wait, did you know that Ranchus’ body anatomy is the major hindrance to their swimming efficiency in captivity? Or that these fish are the outcome of a crossbreed experiment involving the Lionhead Goldfish?

Below, we will be answering all your questions regarding Ranchu Goldfish care at home. We will discuss the fish’s brief history, care requirements, size, appearance, tank size, water parameters, diet, tank mates, breeding, and more.

Species Overview

Carassius auratus or the Ranchu Goldfish were first developed in Japan and China from the crossbreeding experiments involving another popular Goldfish, the Lionhead. Today, the aquarium community boasts multiple varieties, including the black, blue, and orange Ranchus.

ColorRed, Calico, Combinations of gold and white or red and white
Lifespan10-15 Years
Care LevelEasy
Behavior & TemperamentPeaceful
CompatibilityPeaceful Community
Food and DietOmnivores
SizeUp to 10 Inches
Tank SetupFreshwater, Gravel Substrate, and Planted
Tank Size (Minimum)20 Gallons

It’s fair to say that the fishkeeping community hasn’t witnessed many Goldfish varieties that are beautiful in their own right yet so unique in many ways. But such is the Ranchu Goldfish, which, despite its rarity, is fast becoming everyone’s favorite Goldfish in the broader aquarium community.

The Japanese have called it the “king of goldfish,” while the Chinese have kept the parent breed, Lionhead Goldfish, for over a century. But it’s their egg-shaped bodies and arched backs that set the Ranchu Goldfish apart from the rest.

Despite being a member of the Cyprinidae family, Ranchus are a rare breed, and the surest way to get the correct species is to make your purchase from reputable pet stores online.


Keeping the Ranchu Goldfish at home will be a long-term investment. And you will need a lot of space to satisfy their care requirements in captivity.

That being said, the average lifespan of the Japanese Ranchu Goldfish is anywhere between 10 to 15 years with standard care. But they can live for up to 20 years with the best tank conditions in captivity.

Unfortunately, the apparent shortage of diversity and rigorous breeding protocols have combined to lower the fish’s lifespan over the years.

Today, a healthy Ranchu Goldfish thriving under the best tank water conditions will only live for ten years in captivity.

Still, keep in mind that poor water quality and diet may combine to reduce the fish’s lifespan even further.


The Ranchu Goldfish have beautiful egg-shaped bodies, with a large, round head, hence the unique moniker, Buffalo Head Ranchu. These fish have a prominent head growth, sometimes called the wen, positioned just on top of the head.

The same feature will separate a healthy fish from an unhealthy group. But sometimes, the Japanese Ranchu can have more pronounced wens, almost blocking their vision. 

Like the other dorsal-less freshwater fish, the Ranchu Goldfish look smoother and rounder, but the biggest challenge with that configuration will be to balance their bodies in the water.

You see, the role of the fins is to keep the fish stable in water and prevent the possibility of rolling or toppling over when swimming. So, with the absent dorsal fins, the Ranchu Goldfish will have trouble with swimming efficiency, speed, and acceleration. 

That aside, the deep, well-tucked tail is quite rare in most freshwater fish. But it perfectly complements the Ranchu Goldfish’s captivating look in home aquariums. Plus, these fish have a range of primary colors, from black to white, blue, and red.

Most of the Buffalo Goldfish species from local fish farms will have two or more color combinations with metallic or nacreous fins.

But in general, most species will have a bi-color combination of gold and white or red and white. It’s their stunning look in captivity that will make you ignore the other Goldfish varieties to focus on the Ranchu varieties alone.


Ranchu Goldfish can reach 6-12 inches in home aquariums. But with ideal conditions, they can even reach 18 inches in captivity.

However, the fish’s average size will depend on different factors such as genetics, diet, sex, and age.

Like most Goldfish species, the Ranchu Goldfish need enough space because they like to roam freely in the tank if they are comfortable. Plus, a large swimming space will help you maintain high-quality water throughout the fish’s lifespan.

Ranchu Goldfish Care

Ranchu Goldfish is one of the most beautiful Goldfish species in the aquarium community. But they require more comprehensive care than most other freshwater fish due to their delicate nature.

While their hardy nature readily endears them to many aquarists, Ranchu Goldfish require proper grooming as an essential requisite for a neat appearance.

But that’s too taxing for beginners. And caring for these fish at home would be a lot more fun if you avoided the grooming process and other treatments altogether.

Unfortunately, the Ranchu Goldfish must deal with the harsh reality of rolling over when swimming and overfeeding in captivity because of their unique body shapes. So, if you don’t get the basics right, you could be in for a rough ride. 

You can maintain your Ranchu Goldfish in perfect health by providing the right water conditions while monitoring their diet. This implies proper filtration, adequate aeration, and high-quality food are all part of effective breeding.

You should avoid anything that would increase the stress levels inside your Ranchu Goldfish’s habitat. And that means loud noises, fast-moving fish, and incompatible tanks mates should never be part of a Ranchu Goldfish’s ideal habitat.

In the forthcoming paragraphs, we will discuss the basic care guidelines in more detail.

Tank Size

Even with their unique anatomy, everything is pretty exciting if you maintain the right tank size when keeping the Ranchu Goldfish in a confined setting. And a 20-gallon water tank is necessary to accommodate a single Buffalo Goldfish in captivity. Later, you should include an additional 5 gallons for every tank mate you introduce to the same habitat.

Always remember that the exact tank size will depend on the actual number of fish you intend to keep at home and the approximate fish’s size from the start. 

Water Parameters

Fancy Goldfish are temperate fish species that usually thrive in cooler waters. And the Ranchu Goldfish will be no exception.

These fish can readily tolerate slight changes in water temperature, but that’s never advisable in the long run. If you keep the Ranchu Goldfish at home, be sure to maintain the following parameters at the recommended levels:

  • Water Temperature: 68°F-72°F
  • pH Levels: 6.0-8.0
  • Water Hardness: 4-20 dGH

What to Put in Their Tank?

The Ranchu Goldfish are already compromised by their unique anatomy and are not even the most agile species out there. So, you don’t want to complicate their lives even further by choosing the wrong decorative elements.

For effective tank décor, the perfect starting point will be the ideal substrates. And here, we recommend moderately sized gravel or sand if necessary. Gravel, in particular, may provide value for money with its longevity and matchless aesthetic appeal.

Also, natural plants should be part of the Ranchu Goldfish’s habitat. These are an excellent choice to help maintain high water quality besides enriching the Ranchu Goldfish’s diet.

Remember, these little goldfish crave soft edible plants. That’s why you should only consider soft plants like the Cabomba and Elodea if you keep your fish in an outdoor pond. Popular epiphytes like java moss, java fern, and anubias are just enough to keep your lovely Goldfish busy in a standard home aquarium.

Finally, keeping the ammonia and nitrate levels in control is important to sustain the Ranchu Goldfish’s lives for many years. Consequently, proper filtration will be essential for the fish’s survival and optimal growth.

Common Diseases

The Ranchu Goldfish might be popular for their hardy nature, but different conditions within the aquarium community can combine to break their resilience. If you keep these fish at home, you should focus on their diet and tank water conditions; the most common routes for contracting new infections. 

Like most Goldfish varieties, the Buffalo Goldfish are vulnerable to swim bladder disease. This condition is caused by bacteria or constipation and can affect the fish’s mood in captivity.

The most troublesome issue with swim bladder disease is that it never goes away, even with common antibiotics. So, you will want to consult an expert if the symptoms continue.

Fin rot is the next disease you will want to keep away from your Ranchu Goldfish in captivity. This is a bacterial infection caused by Pseudomonas fluorescens and leads to progressive rotting of the fish’s fins.

Sometimes, the fin rot disease has a fungal origin and will present with even rotting fins at the edges. Again, this condition is directly linked to poor water conditions, even though stress might also play a role in catalyzing its spread inside the aquarium.

Finally, an Ich diagnosis can be made by looking out for visible, white spots in the fish’s body and gills. In addition, this condition causes frequent rubbing of the fish’s body against tank objects, uncharacteristic behavior, and loss of appetite.

Before choosing an over-the-counter antibiotic to manage the Ich symptoms, be sure to rule out a non-parasitic involvement that would also present with visible, white spots on the fish’s body.

Aside from the above-mentioned conditions, you will want to pay attention to any unusual behavior inside the aquarium. To improve your Ranchu Goldfish’s health and well-being, always strive to maintain high-quality water while feeding your fish the right meal.

What Do Ranchu Goldfish Eat?

Ranchu Goldfish are omnivorous species with clear feeding habits as long as it is high-quality food. Ranchus enjoy animal and plant-based foods and won’t be selective inside the aquarium.

If you keep the Buffalo Ranchu at home, it’s advisable to diversify their meal to ensure they are getting all the relevant nutrients they need for proper nourishment and growth.

Even then, don’t ignore their staple diet of pellets and flakes. Later, you can get the right food choices to enhance the fish’s diet.

Small insects and worms are some of the best options besides regular live or frozen foods such as tubifex, baby brine shrimps, and bloodworms. In terms of the vegetable choices, spinach and zucchini would greatly make a Ranchu Goldfish’s day.

Behavior & temperament

The Ranchu Goldfish is a calm and peaceful species. However, their anatomy compromises their activity inside the tank, making them easy targets for larger and more aggressive species occupying the same aquarium.

The ideal Ranchu Goldfish tank mates should be peaceful and slower species that won’t create much stress inside the aquarium.

Because of the prominent head growth, Ranchu Goldfish have reduced vision and may stumble upon the tank objects when swimming.

So, you will want to eliminate all the potential dangers inside the tank, such as sharp objects, to prevent injuries. Seemingly, their poor vision is the only explanation for their slow eating rate. 

Ranchu Goldfish Tank Mates

Ranchu Goldfish’s worst tank mates are aggressive or fast-moving fish that would make them quite uncomfortable inside the tank.

In general, Ranchus are highly sociable and peaceful fish that would never look for trouble with other species in the same habitat. And on that note, some of their best tank mates will include the following:

Even with their peaceful temperament, we strongly discourage keeping many Ranchu Goldfish together because the outcome can be appalling.

The male Ranchus can become quite territorial when kept in the same space and will display this trait with endless fights inside the tank.

Also, you will want to introduce any newcomer to the Ranchu Goldfish’s habitat cautiously as you monitor their relationships over time.

In doing so, the fish’s mannerisms within the first few weeks will help you decide whether to introduce a new tank or maintain the same community.


Let’s face it. Breeding the Buffalo Ranchu in a confined setting can be challenging. Of course, it is not entirely impossible to pull off but requires additional effort to accomplish.

Generally speaking, the most challenging aspect of breeding these fish in captivity is sexing. There are no clear-cut differences between the male and female Ranchus. And unless you squint hard enough, you won’t notice the subtle differences in species size and behavior.

As a general guideline, the male Ranchus will have tubercules in maturity while the females are easily recognized by their plump bodies that are more noticeable during the spawning period.

Still, if spawning in the Ranchu Goldfish were to occur, the adult species would automatically want a perfect hiding spot for the female to lay her eggs. Then, the male Ranchus would fertilize the eggs by releasing their sperms in the water.

Unfortunately, these fish aren’t the parental types, so you should keep the freshly laid eggs in a new tank for safety and successful breeding. Typically, the eggs will hatch after 2-3 days with pristine aquatic conditions.

During this period, the little fish will happily feed on infusoria before switching to brine shrimps as they mature.

Final Thoughts

When you think about the Fancy Goldfish varieties, you will doubtless visualize beauty and value for money. And that sums up the Ranchu varieties perfectly.

Ranchu Goldfish is a special aquarium fish with everything you could be looking for to brighten up your tank. Be it ease of care, beauty, or a charming personality, these little Goldfish are the personification of easy-peasy care requirements. They only need the right tank conditions, and you will have built the dream aquarium in no time.

Now that you have learned what’s involved in Ranchu Goldfish care, we can only envision a perfect bond with your little Goldfish friends when you finally choose to keep one at home. Until then, we will be delighted to hear your story with other Goldfish varieties.