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Ryukin Goldfish Care: The Complete Guide

If you’re a Goldfish lover, you really are spoiled for choice! With so many colors and body shapes available, how can one know which Goldfish will work best?

While fancy Goldfish are lovely, many are disease-prone and expensive. And while common Goldfish are inexpensive and hardy they sometimes don’t have the flair of their tank bred cousins.

But what about a Goldfish variety that combines the hardiness of common Goldfish with the flair of fancy breeds?

What are Ryukin Goldfish?

As you likely already know, Goldfish are of Chinese origin. Thousands of years ago food carp were selected for color in what is now China, and the ancestor of the modern Goldfish was born.

Ryukins are actually of Japanese origin, as their name hints. The Ryukus are a group of Japanese islands that stretch between Taiwan and the main islands of Japan. Goldfish made their way from China along this island arc, growing in popularity and new forms developing along the way.

The body form of Ryukin betrays their fairly recent origins – they enter the written literature sometime between 1700 and 1800; much later than many other contemporary Goldfish breeds. While they have a humped back and double tail they are undeveloped compared to Moors, Orandas, Ranchus, and other fancy Goldfish breeds.

This lack of intense inbreeding has a plus side, however. Ryukins are hardier than the average fancy Goldfish. Less prone to disease and chills, they make ideal pond Goldfish as well as indoor aquarium fish!

What else is there to discover about Ryukin Goldfish care?

  • Common Names: (Japanese) Ryukin, Japanese Fantail, Nagasaki Goldfish
  • Scientific Name: Carassius auratus
  • Origin: China (Japanese breed)
  • Length: 6-10 inches
  • Aquarium Size: 20-40 Gallons
  • Temperament: Peaceful
  • Ease of Care: Very Easy

Ryukin Goldfish Care

This section covers everything you need to know about Ryukin Goldfish aquarium size, water parameters, tank setup, and more.

Aquarium Size

Ryukins are big bodied fish and completely bust the inch per gallon myth. A 6 inch Ryukin might match six 1 inch Neon Tetras for length. But the Ryukin creates far more waste load by virtue of its larger body mass.

Therefore, a 20 gallon aquarium should be the absolute minimum you keep an adult Ryukin in. While chunky they don’t swim particularly fast, which reduces their space requirements.

However, keeping larger Ryukins or additional tank mates does add to the bioload. 30-40 gallons is a safer minimum estimate for an 8-10 inch long Ryukin.

Water Quality

Ryukin are some of the hardiest fancy Goldfish. Some, such as Orandas and Black Moors, are prone to getting infections in their overgrown heads and eyes. Ryukins have humped backs but are still much more similar to their wild origins.

You should always aim to keep ammonia, nitrite, and nitrate as close to 0ppm as possible. While Ryukins aren’t especially sensitive these waste products are still harmful and impact fish health even in trace amounts.

Temperature-wise, Ryukins are very flexible as well. Fancy Goldfish are often raised indoors, even in tropical temperatures of up to 75℉. I’d be careful with introducing a Ryukin that’s been raised in tropical climates its entire life into an outdoor pond.

So long as you do so slowly, it will acclimate with time. Once fully adapted Ryukins can overwinter like most other Goldfish, going into hibernation once the water approaches freezing.

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Chemistry-wise, Ryukins prefer the same conditions as other Goldfish. The pH should be neutral to alkaline (pH 7.0-8.0), with slight acidity being acceptable as well. A touch of aquarium salt also bolsters the immune system, stimulates the slime coat, and improves gill function and ion exchange.

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I highly recommend using large hang on the back or canister filters for adult Goldfish. By disturbing the substrate and putting out so much waste they have a larger bioload than most aquarium fish.

With their customizable media baskets for bio, mechanical and chemical filtration, canister filters work especially well for thick-bodied fish like Ryukins.

Plants and Substrate

Goldfish can be a real hassle when trying to keep live plants alongside them. Like most carp, they love nothing better than to dig all day. By rooting at the substrate they continually disturb plant roots and even nip and uproot them once loosened.

Your Goldfish are looking for worms and other aquatic snacks in doing so. Soft plants like Cabomba and Anacharis are also eaten directly by them. If you intend to keep plants along with Goldfish, you’ll need to choose carefully.

Besides the ones in the above list, epiphytes in general are perfect plants for digging fish like Goldfish and Cichlids. An epiphyte is any plant that attaches itself to a hard surface instead of burying its roots in the gravel.

In aquariums, the most popular epiphytes include Java Fern, Java Moss, and Anubias. These plants are also excellent low light plants for aquariums that don’t have dedicated full-spectrum plant lighting, such as most Goldfish tanks.

When it comes to substrate choices, I prefer gravel for Goldfish tanks because of their digging tendencies. Sand is simply too easily moved and you’re guaranteed to have holes and piles all over the place within a week.

Sand also tends to prevent debris from filtering between the grains, leaving exposed detritus and sizable chunks of Ryukin poop.

Tank Mates for Ryukin Goldfish

Goldfish are some of the most peaceful and laid back fish you can own. They pretty much ignore even each other unless they are in a mood to breed. While they may inhale an especially tiny fish, such as a Guppy, most smaller fish are too quick to be easily caught.

Good Tank Mates for Ryukin Goldfish

  • Livebearers, Tetras, Gouramis, and other Tropical Community Fish
  • Barbs, Danios, and other Cyprinids
  • Other Goldfish and Koi
  • Dojo Loaches

Usually, you should be much more concerned with keeping aggressive fish away from your Ryukin. While Cichlids and other bad actors are obviously out, there are other fish that might surprise you.

Many algae eaters, including Chinese Algae Eaters and Plecostomus, are real problems for Goldfish. Both fish love to latch onto slow moving fish and nibble on their slime coats.

Ryukins are just too slow to avoid them – you’re much better off with Dwarf Otocinclus or Siamese Algae Eaters for (heated) Goldfish tanks!

Poor Tank Mates for Ryukin Goldfish

  • Large Cichlids
  • Aggressive Catfish
  • Red Tail Black Sharks and other Territorial Bottom Dwellers
  • Plecostomus and Chinese Algae Eaters

Feeding Your Ryukin Goldfish

Ryukins are like any other Goldfish when it comes to feeding! They will eat just about anything you care to offer them, even bread, though I don’t recommend it. Instead, keep on hand a variety of fresh and prepared options.

Fresh foods include parboiled zucchini and spinach, nori sheets (Japanese seaweed), and inexpensive aquarium plants like Anarcharis. You should also include animal protein like brine shrimp, bloodworms, and earthworms.

For prepared foods go with high quality flakes or pellets. When young flakes soften quickly and are easier for baby Goldfish to eat. As they get larger, pellets are usually a better option for adult fish. However, I always recommend buying soft or pre-soaking your pellets.

Fish pellets continue to absorb water even after being swallowed. A large Ryukin with a belly full of dry pellets can get serious compaction issues, blocking the intestinal tract and causing fatal bloating.

Sexing and Breeding Ryukin Goldfish

Breeding Ryukins is thankfully, just as easy as it is for any other Goldfish. So long as you keep your water quality in decent shape, provide thick tangles of live or plastic plants for their eggs to be deposited in, and feed them a wide variety of foods, you’re bound to have eggs eventually.

Sexing Goldfish can be a bit of a challenge. Unfortunately, the best time to tell is when the adults are in the mood to spawn. Male sexually mature Goldfish develop breeding tubercles, white bony projections on their gill covers and foreheads.

While young males sometimes don’t develop many and females may develop a few, a fish covered in them is almost certainly male! Females also round out substantially when carrying eggs.

Also, males become amorous and competitive when ready to breed, chasing each other and females with gusto! Goldfish are much easier to breed in outdoor ponds as they respond hormonally to seasonal temperature variations.

The fry are also much more likely to survive. As egg scatterers, Ryukins don’t care for their young in any way. By rooting about and tasting everything they will eventually eat their eggs and fry in any but the most heavily planted aquariums.

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Jason Roberts
About Jason Roberts
Jason is an aquarium fanatic that has been a fish hobbyist for almost three decades.

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