Ryukin

Identification

The ryukin’s silhouette is all about the back. Immediately behind the head the body rises in a steep hump, so the profile climbs almost vertically before the dorsal fin, and the body beneath is deep and compressed from side to side, often nearly as tall as it is long. The small, pointed head exaggerates the hump further.

The dorsal fin is tall and the tail is double. Short-tailed ryukins carry a stiff, fanned tail that keeps them agile; long-tailed lines, sold in some countries as fringetails, trail a tail that can be as long as the body.

Red and white in bold patches is the classic colour, but solid red, white, calico, chocolate and tricolor fish are all common. A young ryukin can be mistaken for a fantail, which shares the dorsal fin and double tail; the hump is the tell, and a fantail’s back is a smooth egg shape with none. An oranda shares the tall body but carries a hood and a less pronounced shoulder, while a ryukin’s head is bare and pointed. Young fish of all three look alike, because the hump arrives with growth.

Ryukin, fantail or tamasaba?

• 

  Ryukin

  A hump behind the head

• 

  Fantail

  A smooth egg shape

• 

  Tamasaba

  A ryukin’s back, one tail

Three deep-bodied goldfish side by side: a ryukin with the hump behind its head ringed, a fantail with its smooth back ringed, and a tamasaba with its single long tail ringed.

1. Ryukin. The back climbs sharply behind the head before the dorsal fin, on a deeper body. In a young fish the hump is slight, so judge body depth too: the British standard asks for about 80% of body length in a ryukin and 65% in a fantail.
2. Fantail. The body rises in one smooth egg shape with no hump, over a double tail.
3. Tamasaba. A back that rises behind the head like a ryukin’s, with a full dorsal fin, but a single undivided tail, which in the photograph is a long one.

Photographs: Ryukin, Lerdsuwa, CC BY-SA 3.0; Fantail, ProjectManhattan, CC BY-SA 3.0; Tamasaba, Desaix83, after Ghasem1122, CC BY-SA 3.0. Rings added.

The varieties

The differences are in the fins and the colour; the body is the constant.

• Short-finned ryukin. A rounder fish with a short tail, bred mainly in China; Japanese lines carry longer fins.
• Long-finned or ribbontail ryukin. Draping fins that can approach the body in length. Slower, and far easier to damage.
• Red-and-white. The classic pattern and the one most lines aim at.
• Calico and tricolour. Nacreous scales with blue, red, black and white.
• Chocolate and white. Less common colour lines.

The hump, and what it is not

The defining feature, and the source of a recurring false alarm.

The hump is conformation, not a growth. It is a deep shoulder rising behind the head, bred for over generations, and it develops as the fish grows rather than appearing suddenly. A three-centimetre juvenile may show almost none of it.

It is not a tumour, an infection or a swelling. Nothing needs doing about it, and lumps, growths and tumours covers the things that genuinely do.

But it hides something worth checking. A steeply arched back is very good at disguising a spine that curves sideways, which is a different matter entirely. The test is to look down the length of the fish from directly above: the hump should be symmetrical and the spine straight. Bent spine and deformity covers what a real curve means, including the stunting and mycobacteriosis cases.

How it develops

The shoulder is the point of the breed and the last thing to arrive, which makes a young ryukin an easy fancy to buy by mistake. The hump is slight in juveniles and develops with age.

So a young ryukin and a young fantail are hard to tell apart, and the hump is the last thing to arrive rather than the first. Buying on the promise of a line is the argument breeding goldfish makes.

The hump develops with maturity. Show standards treat a steep hump as desirable and breeders often feed protein-rich food for it, but there is no shortcut: a ryukin fed more than it needs fouls its water and is easy to overfeed, and overfeeding goldfish shows up as a physical problem as well as a water-quality one.

Choosing one

1. From above, down the length. A straight spine, an even body, a symmetrical hump. This is a very useful check on this breed, because the arch hides a curve.
2. From behind. Two even tail lobes, carried apart.
3. Watch it swim. Level, without visible effort. A juvenile that floats, sinks or lists may not grow out of it.
4. Watch it eat, if you can. A ryukin that is not first to the food in a shop tank is worth a second look.
5. Read the shop, as choosing and bringing home a goldfish sets out, then quarantine for at least four weeks.

Where you will find one. Common in aquatic shops, though juveniles are regularly mistaken for fantails, including by the shop — the shoulder hump that defines the breed develops with age and is slight or absent in a young fish. Check the dorsal height and the body angle rather than the hump. The short-tailed form is what you will usually see; broadtail and long-finned ryukins are a specialist purchase.

Personality and behaviour

Among fancy goldfish, ryukins are the confident ones. They are often quicker off the mark than orandas or telescopes, notice food first, and will happily shoulder a slower fish away from a pellet. This is not usually aggression: goldfish are not territorial, and a ryukin competes for food rather than fighting. It simply eats faster and pushes harder.

Which makes it a stocking decision rather than a behaviour problem. A ranchu, a bubble eye, a celestial eye or a heavily wenned lionhead will lose every meal to it over months, and chasing and bullying covers that quiet mechanism and the feeding tactics that mitigate it. Good company is a fantail, an oranda or another ryukin — fish of comparable speed and confidence. And it is not a fish for a single-tail tank either, in the other direction: a comet still outpaces it.

Aquarium requirements

Ryukins grow larger than most keepers expect. Allow 100 litres (26 US gallons) for the first fish and 40 to 50 litres more for each additional ryukin; a fish that reaches 25 cm will use every litre of a bigger tank. Length and width matter more than height, because a wide footprint gives more swimming room and more surface area for gas exchange. The tank size calculator runs the numbers for your own group.

Filtration should be generous, because a fish that eats this enthusiastically produces waste to match. Choose a filter rated well above the tank’s volume and soften the outflow with a spray bar or baffle so the tall dorsal fin and long finnage are not blown about. Keep the water between 18 and 24 °C (64 and 75 °F), keep it stable, and change 25 to 40 percent weekly according to nitrate readings.

Decor should be smooth, since a deep-bodied fish that turns sharply catches fins on rough edges, and sand or a bare bottom removes the risk of swallowed gravel.

Feeding

A quality sinking pellet formulated for fancy goldfish should form the base of the diet. Ryukins gulp floating food at the surface, and the air that comes with it is often blamed for floating problems in deep-bodied fish; sinking food removes that issue at a stroke.

Feed small amounts two or three times a day, only what disappears within a minute or two, and watch that slower tankmates get their share; spreading pellets across the tank helps. Blanched peas, spinach and zucchini, gel foods and occasional frozen daphnia or brine shrimp round out the diet. The feeding calculator gives a starting portion.

Common health considerations

Ryukins are relatively robust for a fancy breed, and a well-kept fish is often trouble-free for years. Their weakness is the shape that makes them attractive: a short, tall body packs the organs into less space, and the swim bladder, which sits above the gut, is affected by whatever happens below it. A gulp of air, a large dry meal or constipation can leave a ryukin tilting, floating or resting on the bottom. Some episodes settle with sinking food, a day without feeding and a few shelled peas; persistent problems are covered in the floating guide.

Because they eat so readily, ryukins are also easy to overfeed, which shows up as a swollen belly, stringy waste and fouled water. Sudden swelling with raised scales is a different matter and should be checked against the swollen abdomen guide. Tall dorsal fins and long tails tear on decor or in strong current; clean water heals most tears, but fix the cause.

The deep body, and what it costs

Everything distinctive about keeping a ryukin follows from one fact.

A shorter body changes the arrangement inside it. In a comet the gut runs the length of a slim body; in a ryukin the same organs sit in something almost as tall as it is long, and the swim bladder shares that space. Goldfish anatomy and biology covers the arrangement, and goldfish nutrition covers what a stomachless gut can actually process.

So a ryukin may be prone to buoyancy trouble, although one breed standard says ryukins seem less susceptible than many other deep-bodied fish, and the trigger is often the meal rather than a disease.

The precautions are mostly dietary:

• Soak dry food for a minute before it goes in, which may reduce swelling inside the fish.
• Feed sinking, which stops the air-gulping at the surface — sinking versus floating food.
• Add vegetables a couple of times a week for the fibre.
• Feed small and often rather than one large meal.
• And consider gel food, which is soft, moist and the easiest thing a deep-bodied fancy can process.

Floating upside down covers what to do when it happens anyway, and constipation the related picture.

What goes wrong, in order

What you see	Usually	Where to look
Floating or tipping after meals	Often the meal, though other causes exist	Floating upside down
Long trailing faeces	Dry food, not enough fibre	Constipation
A curve seen from above	Not the hump — a real deformity	Bent spine
Split or frayed fins	Sharp decor, or strong flow	Torn fins
A slower tankmate going thin	The ryukin is eating its share	Chasing and bullying
Resting low, fins clamped	Water quality or temperature	Sitting on the bottom

Two of those six are about food and one is about the fish it lives with, which is a fair summary of ryukin keeping: the tank is rarely the problem, the feeding usually is.

Is a ryukin right for you?

It suits you if you want a striking fancy with real presence, you will feed deliberately — soaked, sinking, small and often — and you will keep it with fish of similar speed.

It does not suit you if the tank holds slow fancies it would outcompete, if you want to scatter floating flakes and walk away, or if you have not yet got a routine for water changes. It is not a difficult fish; it is a fish that punishes casual feeding.

And the deep body is a real cost, in the terms goldfish welfare sets out. The moderate ryukins are a good deal easier to defend than the most extreme show lines, where the compression is taken further than the animal comfortably manages.

History and origin

The ryukin takes its name from the Ryukyu Islands, the chain that includes Okinawa. Deep-bodied, double-tailed goldfish of this type were bred in China and reached Japan through the Ryukyu Islands in the 1770s or 1780s, and Japanese breeders developed the type further; some accounts make it a mutation of the wakin. It remains popular in Japan.

Ryukins spread to Europe and North America with the wider goldfish trade of the late nineteenth and early twentieth centuries. Today they are bred widely in Thailand, China and Japan, and show fish are bred for steep humps. The ryukin body has also been used to build other varieties, including ryukin-bodied telescopes.