Home Goldfish Black Ranchu Goldfish: Tank Size, Care, Breed, And More

Black Ranchu Goldfish: Tank Size, Care, Breed, And More

Black Ranchu Goldfish

Black Ranchu goldfish is a popular freshwater goldfish that goldfish lovers around the world widely love. Their fascinating and unique appearance and distinctive behavior make them prominent among other goldfish types, making it a joy to watch and care for them. 

Due to its prominent head, round body, and wavy back, it is known as the “king of goldfish.” In this article, we will discuss in detail its major characteristics and everything from its care to its maintenance. 

You will love to explore this captivating water creature if you are an aquarist or a beginner who wants to keep goldfish. There are many new and exciting things to discover, and we will explore them in this post.

Black Ranchu Goldfish

One of the most prominent features that make them different from other goldfish types is that they have no dorsal fin and have a head outgrowth known as Wen. Lack of dorsal fin makes them slow-moving water creatures, and they have to rest throughout the day to regain energy for proper swimming.

They are handicapped but a peaceful goldfish type commonly seen in pet stores, and you can purchase one directly from reputable breeders. Their unique characteristics and distinctive body shape never come in the way of making their surrounding social and secure with other tank mates, and that is their specialty. 

Delicate bodies and nature require extra care, and they become more prone to diseases and stress if they are kept in a bare, unfiltered tank.

How Much Do Ranchu Goldfish Cost?

The price range of Black Ranchu goldfish varies with age, size, and availability. You can get it between $5 to $25. If you buy it from a pet store, it is a better idea with cheap rates but remembers to check the health of your new goldie from some vet. Pet stores often have low-quality fish which are not properly bred; for a healthy Black goldfish, you can approach a nearby reputable breeder.

Physical Characteristics of Black Ranchu Goldfish

NameCarrassius Auratus
Size5-8 inches 
Life span10 to 15 years
TemperamentPeaceful and social

As the name suggests, the Ranchu we are talking about is black in color, but other Ranchu goldfish are of different colors and patterns with metallic scales. Remember, the color of black Ranchu goldfish fades or changes throughout their life, and they can take shades of many colors. The color of the Rasbeerry-shaped Wen is also black, which doesn’t look different on their head because of the same color, and you cannot recognize it easily without keen observation. Sometimes the development of head growth is so much that it covers their eyes and thus contributes to a lack of agility.

Habitat and Tank Requirements for Black Ranchu Goldfish

The Black Ranchu goldfish is a peaceful, social, and slow-moving water creature. During the day, you can see this lovely goldfish type searching the substrate for any discarded food. They rest at the bottom of the tank or swim in the water to explore and investigate the surroundings because it is their favorite hobby. 

Tank requirement

Ranchu is a large goldfish, so you need to have more space for the one in your home. The tank requirement for Ranchu goldfish is as follows:

Tank/Aquarium Size:

A minimum tank size for an adult black Ranchu goldfish of 10 gallons is required, and if you want to have another, then an addition of more than 5 gallons is required. However, the size of the tank varies; it depends on how big or small the goldfish you plan to put in your tank. 

Water Temperature And Ph

Black Ranchu require a constant water temperature; thus, they will feel comfortable between 65°-77° Fahrenheit, and the required PH of the water is between 7.2-7.6. Remember that Black Ranchu is a temperate water goldfish. 


For your Black Ranchu fish tank, the best choice is appropriate size gravel and sand. Keep in mind that because Ranchu forages for food, the gravel should be big enough to prevent your goldfish from choking. This is why we must provide a safe substrate; that’s why bare-bottom tanks are not recommended.  


A variety of decorations in an Aquarium is good for your goldfish, especially if they are plants. They are advantageous, contribute to maintaining the quality of the water, and enhance the diet of fish. Soft, edible plants are a favorite food of Black Ranchus.


You need a filter of a suitable size because it maintains the required water. It is important to ensure that the filtration system can handle a higher volume of water than the current tank size and to perform regular water changes that are appropriate for the bioload and water parameters of the aquarium. This will help to maintain a healthy and balanced aquatic environment for the fish and other inhabitants of the tank.


If your aquarium is placed in the dark, buy an aquarium light to give them proper light time. If your aquarium is placed where there is sunlight or another light, then change the place because the darkness is needed, as Black Ranchu needs 8 to 12 hours for rest.

Diet and Feeding Habits of Black Ranchu Goldfish

High-quality pellets are a great option for black Ranchu when feeding this charming water beauty. Pellets that are a mix of protein, fat, and fibers are a proper balance diet for Black Ranchu. 

Avoid brands that have fillers or artificial preservatives in goldfish food. Flakes are another option, but it is not a good choice because they tend to gulp air-feeding from the surface. But if you want to feed them flakes, then use high-quality and specifically formulated flakes for goldfish. 

Black Ranchu are omnivores and loves to have vegetables in their diet. Small pieces of blanched zucchini, spinach, or peas are a healthy supplement added to their daily diet.

Moreover, live or frozen foods like daphnia, brine shrimp, or bloodworms can be a great source of protein for black Ranchu goldfish. Be sure to avoid overfeeding, as these foods can be high in fat and affect the health of your Black Ranchu.

Breeding and Reproduction of Black Ranchu Goldfish

Black Ranchu breeding is best possible in spring when the temperature is right and with appropriate healthy mates. Ranchu, in general, is ready to breed between 1 to 2 years old and spawn in warm water conditions. 

Mates show breeding stars when they are ready to breed. Male goldfish chase the female Black Ranchu showing breeding behavior. Keep in mind that males do not constantly chase females because this behavior of males stresses them out. 

In order to stop this behavior, it is suggested and highly recommended to use a tank divider and separate the genders. When the breeding season and age of the black ranchu come along, they make visual barriers and proper hiding places to avoid the constant stress of mating behavior.

Common Health Issues and Diseases in Black Ranchu Goldfish

Ranchu is also susceptible to health issues and diseases like other fish types. Some prominent health issues that badly affect your finny friend’s health are

Fin Rot:

It is a type of bacterial infection that can cause the fins of Black Ranchu to deteriorate and develop ragged edges. 

Mouth Fungus:

In this type of fungal infection disease, the mouth and lips of Black Ranchu goldfish become swollen and discolored. 


It is a bacterial infection in which black Ranchu develops swollen belly and protruding scales. 

Swim Bladder Disease: 

Swim bladder causes the fish to swim difficulty and can lead to floating at the surface or sinking to the bottom of the tank.

Ich Disease: 

Ich Disease is a particular parasitic infection that can cause white spots on the skin and fins of the Black Ranchu Goldfish.


Velvet is a type of parasitic infection that can cause the Black Ranchu Goldfish to develop a yellow or brownish film on its skin and fins.

Tips for Keeping Black Ranchu Goldfish Healthy 

After knowing the most prominent health issues of black Ranchu, it is important to ponder some tips to keep your goldfish happy and healthy. These tips are as follows:

Keeping a Ranchu goldfish happy and healthy is easy. It is possible by ensuring that the water condition in a fish tank or aquarium is high quality. 

It requires a good filter and has adequate aeration and cycled tank. Water changes are also necessary to keep them healthy.

Good quality and proper diet are essential to caring for the black Ranchu . 

You can also keep your pet friend healthy and happy by keeping them away from tank jostling, loud noises, or frequent quick movements to avoid stress. 

Peaceful and compatible tank mates also contribute to a healthy and safe environment around black Ranchu goldfish. If you notice any symptoms and signs of illness in your Black Ranchu Goldfish, it is important to take action quickly and seek advice from a veterinarian or a fish expert.

Differences between Black Ranchu Goldfish and other Goldfish Varieties

Black Ranchu is a unique variety of goldfish with many distinct characteristics from other goldfish varieties. 

  • Black Ranchu has a round body with a slightly curved back. In contrast, other goldfish types have streamlined bodies, such as common goldfish.
  • The tail of this charming water creature is short and round, while others have longer and more flowing tails, such as fantail. 
  • As per the name, the black Ranchu is black with some gold and orange markings on its head and fins, while other goldfish types are of different colors, with some available in bi or tri-color.
  • Black Ranchu have distinctive heads that are concave and have no dorsal fin, but other goldfish have a traditional head shape and have a dorsal fin.
  • Black Ranchu goldfish is a slow swimmer in comparison with other goldfish varieties.

Conclusion: Why Black Ranchu Goldfish is a Popular and Beloved Pet Fish

Black Ranchu is a popular goldfish type for many goldfish pet owners because of its striking appearance and attractive black color. These water creatures are unique and appealing; that’s why fish enthusiasts love them. 

Therefore, if you want to enjoy the beauty of this mesmerizing water creature, then it is necessary to know about its basic characteristics, care, temperament, and many other important things. This article covers every step of Ranchu goldfish. If you want to buy a Black Ranchu goldfish for your aquarium, this post will guide you to make a better decision.

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