Ranchu Goldfish Care Guide - Feeding, Diseases, Breeding and more...

The Ranchu Goldfish is one of the most popular fancy varieties sold.

Ranchu are highly prized in Japan with champion fish commanding very high prices.  With their curved backs, raspberry like head wens, twin tails and no dorsal fin, they produce many challenges for breeders trying to breed high quality fish.

Last Updated: Page under construction by Grant Lord.

Ranchu Goldfish Care

No special care is required for Ranchu except for these important rules:

• Some wens can grow so large that they cover the eyes as can be seen in the image above.  If this happens either the wen should be trimmed or the fish isolated or kept with other fish with similar eye limitations.
  
• Give them a varied diet, especially as they get older to avoid swim bladder problems.

Read on to discover the most common mistake novice Ranchu keepers make.

Ranchu History

All Goldfish varieties can trace their history back to the Prussian or Gibel carp.  Through selective breeding of these fish that developed odd genetic characteristics such as gold coloration and twin tails, all the 100 plus different varieties have been developed.

All Goldfish varieties have the same scientific name of Carassius auratus auratus var. not Carassius gibelio, which is interesting because no variety of Goldfish lives in the wild, (unless introduced intentionally), not even the Common Goldfish.

The Ranchu Goldfish lineage can be traced back to the Maruko or Egg Fish, which was basically a fantail without a dorsal.  The Egg Fish has a direct link back to the twin-tailed Wakin, the most popular Goldfish variety in Japan.

Scale Types of Ranchu Goldfish

The black coloration of the Black Moor Goldfish comes from an excess of melanic pigment deposited in the scales.

Young Moor under 30 days old are a drab gray with normal eyes, but from five or six weeks of age the black pigment begins to appear in some early developers along with the telescopic eyes.

The best Black Moors have a deep velvety blue-black coloration that covers the entire body, including the fins and ventral area.  If Black Moors show an underlying bronziness, they are likely to change color later in life, usually changing to orange or red.  Many Red Moors are just Black Moors that have changed color.  Some experts advise against keeping Moors too warm, either when they are young or when they are adults as warmer water is one of the methods used to make metallic scaled Goldfish change color sooner.

Those with an underlying white or silvery ventral (belly) area will probably remain black throughout their lives.

What Should a Ranchu Goldfish Look Like?

A good quality Ranch has these characteristics:

• The scale type is always metallic, with a deep velvety blue-black coloration that covers the entire body, including the fins and ventral area.
• The eyes should project outwards and slightly forward.  The eyes should be even in size and shape.  The eyes should be prominent with good development in relation to head size.
• The body depth should be at least 65% of the body length.
• All fins except the dorsal are paired.  The tail fins should be divided, even in size and shape with no curled or bent extremities. 

The UK Nationwide Goldfish Standards require Black Moors to be veil tails (also called broad tails) with the tail fins a minimum length of 75% of body length and with no fork.  Most commercial grade specimens usually have tail fins that resemble the Fantail.

The American Goldfish Association recognizes both the veil tail and fish with a forked tail.

Genetics and early fry care dictate the size a Goldfish will achieve.  125mm (5 inches) body length is a good size for a Black Moor. 

Black Moor Goldfish Are a Hardy Fancy Variety

Black Moor are a hardy variety, able to withstand low temperatures better than most of the fancy varieties.  They are often kept with varieties that they can't compete with for food, such as Comets.

Because of their popularity and cheapness, many aquarists make the mistake of using Black Moor Goldfish as a color contrast in an aquarium full of gold colored fish.  Unless the other Goldfish are also telescopic-eyed, Water Bubbles Eyes or Celestials, the Moor won't get enough food so will get weaker and weaker until eventually succumbing to disease or starving to death.

This is why many Goldfish enthusiasts think Moors are a weaker variety that tends to get sick and die.

The lifespan of a Black Moor is no different from any other fancy variety, in fact, when well cared for they can easily live for 10 years in an aquarium, more if living in a pond.  The biggest killer of adult Black Moor is swim bladder disorder.  The condition itself isn’t fatal but it leads to other complications that ultimately leads to death.

Poor diet in older Ranchu is the usual cause of swim bladder disorders.

What to Feed Ranchu

Being deep bodied, they will suffer digestive problems if fed low quality food with not enough vegetable matter and live food included in the diet.  This typically shows up as buoyancy problems with the fish bouncing on the surface with an intestine full of gas.

Gel foods are recommended as they mimic the natural foods of Goldfish which are in the main soft and moist.

Live foods can include mosquito larvae, daphnia, earth worms, blood worms, white worms and adult brine shrimp.

If live food is hard to find or grow yourself, many specialist fish shops have the frozen equivalent.

I wouldn’t collect daphnia from the wild as parasites such as lice can be introduced into the aquarium.

Mosquito larvae are easy to raise and Goldfish of all ages love them.  Check whether you are legally allowed to raise them as in some countries and US states, you can’t.

How much, how often and what to feed your Goldfish depends on age, season, or whether you are conditioning your fish for breeding.

Because Goldfish only have rudimentary stomachs, they graze continuously which is why they always appear hungry.  Ideally, they should be fed 3 times a day, but for most this is impracticable.

Adult fish should be fed between 1-2% of their body weight per day.  If only one feeding a day is possible, a good quality food that won’t dissolve before the fish can eat it is needed.  This is why a gel food such as Repashy Super Gold is recommended.

The danger of overfeeding is often the reason given to feed only what can be consumed in a few minutes.

Fact: Goldfish cannot be overfed! Goldfish are slow eaters compared to some fish species because they only have a rudimentary stomach.  They force as much food as they can into their mouths and then slowly chew and swallow it before looking for another mouthful.

During this period, dry, processed foods are dissolving.  By the time the fish are looking for their 2 or third mouthful, the food has dissolved into dust that will decay and pollute the water.

Maintaining Water Quality

Like all Goldfish varieties, the Black Moor requires good water quality to thrive.  The difficulty with this is Goldfish can become large given the right conditions; when young they need a lot of food to grow quickly which produces large amounts of waste.

The ideal water parameters for Ranchu are:

• pH between 6.5-7.4
• Nitrates below 20 ppm (parts per million).  Very young fish (fry) require nitrates to be below 5ppm.
• Ammonia needs to be at zero
• Nitrites need to be at zero
• Water temperature between 60-75^oF (16-24^oC)
• GH (general hardness) between 130-200ppm (dGH 7-11)
• KH (carbonate hardness) between 89-142ppm (dKH 5-8)
  

Most city water supplies fall into these parameters.  If your water source is from a bore it will pay to check what the water parameters are, as often nitrates and hardness readings can be very high.

You will need a water test kit so you can check your water parameters regularly, and work out when you need to make water changes.  Get a test kit that has test tubes and solutions.  Don’t use test strips as they are notoriously inaccurate.

Making partial water changes without checking whether they are sufficient or often enough is just guessing.

Is a Filter Necessary?

A filter, although not essential, does reduce the maintenance workload.  Water changes must be made much more frequently to keep ammonia at a safe level if a filter is not installed.

A filter, once it is cycled, removes dangerous ammonia and nitrites, creating less harmful nitrates.  A water change becomes necessary once the nitrate level goes above 20ppm, which is why you need a water test kit.

Because Ranchu are not the strongest of swimmers, a filter should turn the aquarium water volume over four times an hour, but should not create a current the fish have to swim against.

Is a Heater Necessary?

Ranchu are warm water fish, not cold water, not tropical, and prefer seasonal changes in temperature.

Goldfish can take very low temperatures but only for a short time such as in Winter when they go into a dormant or low activity state.  Low water temperatures such as these are best tolerated by less developed varieties such as single-tailed Comets and Common Goldfish.

If kept indoors where water temperatures will be well above freezing, a heater is not required.  If Ranchu are kept outside in a pond, and water temperatures are expected to fall below 45^oF (7^oC) for long periods over Winter, it would be wiser to bring them inside for Winter.

Fancy varieties of Goldfish often develop buoyancy problems if subjected to long periods of cold water temperatures.

Suitable Tank Size for Ranchu

Ranchu are not one of the most active varieties, so one Ranchu needs 15 gallons, with a filter installed.

15 gallons is a good compromise between how big the fish will grow, how big the tank is to handle, water temperature swings, and the frequency of water changes needed to keep nitrates below 20 ppm.

For each additional Goldfish, another 10 gallons are required.

If your tank is for display purposes only, get a tank that is slightly taller than it is wide as taller plants such as Vallisneria can be grown and a taller tank has a larger viewing area.

Do not place your tank where it will receive direct sunlight or strong indirect sunlight.  Even strong artificial light can be a problem.  Tanks produce ideal algae growing conditions with their high nitrate levels; all that is necessary to produce an algal bloom is sufficient light.

If you have no option but to place your tank near a strong light source, you can always install a UV clarifier.

Suitable Tank Mates for Ranchus

The most common mistake novice Goldfish keepers make is to mix fancy varieties with single-tailed varieties.  They don't realize slow-swimming varieties such as Ranchu can't compete successfully with fast-swimming varieties for food.

What happens over time is as the single-tailed fish get the majority of the food, they get bigger and bigger, and the Ranchu doesn't thrive.

Ranchus can be kept with other Goldfish varieties but if they are single tailed, a suitable feeding system will need to be devised.

Plecos and Bristle Nose catfish used for removing algae can become a problem if they start eating the slime off the sides of your Ranchu as a protein supplement to their diet.

Any other small fish or aquatic life in the aquarium will be eaten if it can fit into your Ranchu’s mouth.

Suitable Tank Plants

Goldfish are omnivorous meaning plant material forms part of their diet.

If you choose the wrong plants, your Ranchus will strip them to stalks within hours.

Plants that are suitable are;

• Vallisneria - used as a background plant because of the height it grows to
• Blue Hygrophila – used as a foreground plant.  There is a dwarf variety available.
• Hygrophila Difformis – used as a foreground plant.  Its fast growth helps control algae
• Red Bacopa – the leaves get a red tinge on the underside
• Ludwigia Arcuata – this plant requires a relatively large amount of light before forming a red stem and red leaves.

Suitable Tank Substrate (Gravel)

Adding substrate or having a bare bottom tank is a personal choice, but there are some considerations before purchasing substrate;

• White substrate will cause your fish to lose color intensity
• Sand is not a good choice if you want to install an under-substrate filter.  The grains need to be between 3 and 6mm in size.
• Goldfish will choke on small pieces of smooth gravel.  I have lost two Black Moors from this.
• Are you planning on growing live plants?  Plants can be grown in containers if you don't want to have substrate.

Aquarium Decorations

Because of their shortsightedness, Black Moor tend to blunder around an aquarium.  If startled they can easily knock out an eye on any hard objects.  If the aquarium has any sharp edges, the eye structure can be cut.  When this happens, the bodily fluids leak out, and the telescopic eye structure deflates.  It doesn’t repair itself and reinflate, the lens just sinks into the eye socket surrounded by excess skin.

Ranchu Diseases and Injuries

Ranchu are no more susceptible to diseases than any other fancy Goldfish.  In fact, they are one of the hardier ones, but any Goldfish living in poor water conditions will develop a weakened immune system that will allow the fish to be attacked by parasites, bacteria or fungal spores which unless treated, will kill it.

Parasites

There are several types of parasites that attack Goldfish;

• Flukes if the body length of the fish is under 52mm (2 inches)
• Intestinal worms
• Protozoan parasites such as Costia and Ich (white spot)
• Free swimming aquatic parasitical crustaceans such as anchor worm and lice.

Bacterial Diseases

Bacterial infections can show as;

• Fin rot
• Bacterial gill disease
• Mouth rot
• Pop eye
• Raised scales
• Body sores (ulcers)
• Red patches on the body and fins (hard to see on a Black Moor)

Fungal Infections

Fungal infections are quite common in Goldfish.  They are usually seen as large or small tuffs of white cotton wool-like matter on the skin or fins.

A much more serious fungal infection is Branchiomyces which is an aggressive fungus that kills fish by destroying gill tissue.

Viral Pathogens

The two most common viruses are:

• Lymhocystis virus which appears as a white crusty growth on the skin and
• Papillomatous lesions caused by the cyprinid herpes or carp pox virus.

Both look very similar but treatment is different.  Both are weakly transmissible but neither is fatal.

Eye Injuries

The large protruding eyes of this variety are particularly susceptible to damage.  Owners often find their Moor missing an eye.  This can be caused by another aquarium inhabitant or aquarium decorations.

Losing an eye doesn’t seem to particularly bother Goldfish, but I would place the fish into a mild salt bath to guard against any infection and because quite a large amount of blood is lost.

If the fish is eating well and active, it can be returned to the aquarium after a few days.  With a missing eye, it is now at a disadvantage compared to fish with two eyes so during feeding it will need to be monitored to ensure it is getting its fair share of food.

Other aquarium inhabitants, including larger Goldfish, can easily suck an eye out of a Moor, which is another reason why Moors should not be kept with other varieties or species of fish.  A Moor shouldn’t be significantly smaller than other Goldfish in the same aquarium.

Quarantining New Fish

Quarantining new fish does not mean keeping the fish separated from your existing fish population for a few weeks and observing if they develop a disease.

It is highly unlikely fish being kept in pristine quarantine conditions and being fed high-quality food will succumb to any disease.

But what if the fish are carrying a few parasites such as flukes within the gills and not exhibiting any symptoms?

And what if your fish have low immunity to flukes as they have never been exposed to them before?

It should be assumed your new Black Moor has parasites and should be treated for them.  A mild salt bath will take care of any bacterial or fungal infections if any aren’t obvious at the time of quarantining.

An additional benefit of salt is it boosts the immune system of Goldfish.

Breeding Ranchu Goldfish

The telescopic eyes make it harder for the male to find the female.  Don’t clutter the breeding container so the female can hide.  Use as many males as possible per female, the more the better as it also increases fertilization rates.

Male/female differences are less obvious outside the breeding season because of the short round body shape.  Often the female will have a slimmer body shape than the male giving the impression she is a he.

The white tubercles that appear on the male’s operculum (gill plates) and leading edges of the pectoral fins in the breeding season are easily seen against the black coloration.

Ranchu Goldfish Overview

Country of Origin: Japan

Chinese Name: Dragon Eye

Japanese Name: Demekin

Maximum size (body length): 5 inches (125mm)

Body Type: Deep and rounded, depth to be more than half the body length

Caudal Fin: Paired, should be a veil tail to follow the British Standard but usually forked in commercial grade fish and of varying lengths.  The American Standard allows forking of the caudal fins but also recognizes the veil tail variety.

Dorsal Fin: Absent

Anal Fin: Paired

Scale Type: Metallic scale type

Eyes: Normal

Distinguishing traits: Black coloration, deep bodied, telescopic eyes

Special requirements: Not to be kept with normal eyed Goldfish.

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