Ranchu Goldfish

Ranchu Goldfish: Care and Keeping Guide

Ranchu Goldfish are a unique and fascinating breed of fancy goldfish that has won the hearts of many aquarists around the world. With their distinct appearance and entertaining behavior, it’s no surprise that these fish are highly sought-after by both collectors and hobbyists alike. In this comprehensive guide, we will delve into everything you need to know about Ranchu Goldfish care, including tank size, water parameters, tank setup, diet, and much more.

Overview of the Ranchu Goldfish

The Ranchu Goldfish, often considered the “king of all goldfish,” is a product of centuries of selective breeding and belongs to the group known as “fancy goldfish.” Unlike most fancy goldfish, the Ranchu originated in Japan in the 1600s and didn’t make its way to China until much later. Today, these beautiful fish are admired by aquarists worldwide for their unique appearance and regal demeanor.


Ranchu Goldfish are truly one-of-a-kind with their bulbous, egg-shaped body, and distinct curved back. Lacking a dorsal fin, these fish have a pronounced humpback posture. Their expansive double-fan tail creates a stunning burst of plumage, making them a popular choice among goldfish enthusiasts.

The head of the Ranchu Goldfish features a fleshy growth, known as a helmet, which covers the top of the head, gills, and cheeks. This growth can vary in size, with some being subtle and blending in with the fish’s color, while others can be more prominent and even affect the fish’s visibility. Ranchu Goldfish are available in a variety of colors, including the iconic shimmering gold, white, black, and calico.


The average lifespan of a Ranchu Goldfish is between eight and 15 years. However, the quality of care you provide can greatly impact their longevity. Due to their limited genetic diversity, Ranchu Goldfish are susceptible to a wide range of conditions and illnesses. Proper tank maintenance and a balanced diet are crucial to ensuring your fish reach their full potential.


The typical size of a Ranchu Goldfish ranges from five to eight inches in length when fully grown. However, in larger tanks or outdoor ponds, these fish can grow up to a foot long or even reach impressive lengths of 18 inches.

Ranchu Goldfish Care Essentials

While Ranchu Goldfish may not be the most challenging fish to care for, they do have unique care requirements that must be met for them to thrive. Their history of selective breeding also makes them prone to various health issues, making high-quality husbandry a must.

Tank Size

Although Ranchu Goldfish are not powerful swimmers, they still require an adequately sized tank to support their health and well-being. A younger juvenile can be housed in a standard 10-gallon tank, but a fully grown adult will need at least 30 gallons. Many experienced aquarists recommend a tank size of no less than 55 gallons for a single Ranchu Goldfish.

It’s essential to provide your fish with enough space to prevent stunted growth and reduce stress levels. For each additional fish, you should plan to add at least five gallons of tank volume. If you live in a temperate climate, you might also consider housing your Ranchu Goldfish in an outdoor pond.

Water Parameters

Ranchu Goldfish prefer relatively cool waters with a neutral pH balance. They are not fans of fast-moving currents but do appreciate well-oxygenated water. Stability is key when establishing and maintaining your aquarium’s water parameters.

  • Water temperature: 65 to 75 degrees Fahrenheit
  • pH levels: 7.0 to 8.0 (aim for neutral)
  • Water hardness: 5 to 19 DH

Tank Setup

Creating a natural and enriching environment is an essential aspect of Ranchu Goldfish care. Keep in mind that these fish are quite delicate, so avoid any sharp or jagged decorations that could harm their fins or body.

Start with a layer of sand or smooth pebbles as a substrate, as Ranchu Goldfish enjoy digging and moving the substrate around. In general, plants are not recommended for Ranchu Goldfish tanks, as they tend to uproot and feed on them. However, you can try using sturdier plant species like anubias, java fern, or java moss, anchored to rocks to prevent uprooting.

Equip your tank with an appropriately sized filtration system to handle the significant amount of waste that Ranchu Goldfish can produce. Avoid creating strong currents with outlets or pumps, as these can be too challenging for the weak swimmers to overcome. Air stones are beneficial for oxygenation without creating excessive water flow.

Common Diseases

Ranchu Goldfish are often considered sensitive fish, with moderate to high disease risks. Maintaining optimal tank conditions and performing regular water changes can help prevent many health issues.

Common diseases to watch for in Ranchu Goldfish include Ich, velvet disease, and fin rot. Stress is often a factor in the development of these conditions, so ensuring a stable and healthy environment is crucial.

Diet and Feeding

Ranchu Goldfish are omnivores and require a balanced diet to thrive. High-quality flakes or pellets are an excellent foundation for their nutritional needs. Supplementing their diet with high-protein snacks, such as insects, tubifex worms, or bloodworms, can provide additional nutrients and variety.

Feed your Ranchu Goldfish two to three times a day, offering enough food that they can consume within two minutes. Overfeeding can lead to health problems and negatively impact your tank’s water quality.

Related: Types Of Aquarium Algae

Behavior and Temperament

Ranchu Goldfish are known for their calm and easy-going nature, as well as their unique swimming style. Their flowing tailfin creates an elegant display as they move about the tank. These fish are not aggressive and make excellent community fish.

Tank Mates

When selecting tank mates for your Ranchu Goldfish, it’s important to choose cold-water species with a similar peaceful temperament. Avoid larger, aggressive fish, such as Cichlids or Oscar Fish, and steer clear of fin-nippers that would target your Ranchu’s beautiful tailfin. Some suitable tank mates for Ranchu Goldfish include:

  • Weather Loaches
  • White Cloud Mountain Minnows
  • Zebra Danios
  • Hillstream Loaches
  • Other fancy goldfish varieties (such as Orandas, Lionheads, and Bubble Eyes)


Breeding Ranchu Goldfish can be challenging due to the difficulty in sexing the fish. Males will develop tubercles on their gill plates and faces at maturity. Breeders often attempt to breed a group of fish, allowing pairs to form naturally.

Set up a spacious breeding tank with similar conditions to the main tank, adding fine-leaf plants or breeding nets to protect the eggs. After spawning, remove the adult fish, as they have no parental instincts and may eat the eggs.

The eggs will hatch in two to three days, and the fry will become free-swimming after absorbing their egg sacs. Provide the baby fish with powdered or liquid fry food before transitioning them to high-protein meals like baby brine shrimp or infusoria.


Ranchu Goldfish care may not be overly complicated, but it’s essential to get it right. These sensitive fish require particular attention to tank conditions, diet, and overall care to ensure they thrive. By following this comprehensive guide, you’ll be well-prepared to meet the needs of your Ranchu Goldfish and enjoy their unique beauty for years to come. If you have any questions or concerns not addressed in this guide, feel free to reach out for assistance.

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