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Looking for a fish that is both cute and rewarding? This Ranchu Goldfish care guide will show you all about how to look after these cheeky-looking pets. The name ‘ranchu’ is Japanese for ‘Dutch worm’, as these fish arrived in the country from China via Dutch traders. In addition, you may hear them named ‘Lionhead Ranchu Goldfish’.

This goldfish variety comes in many colors, from the black ranchu goldfish to red, orange, and even bicolor versions. They are more delicate than their flat-bodied relatives, but in competent hands, they make great companions. Read on for full information on how to take care of Ranchu Goldfish.

Ranchu Goldfish Care: Setting Up Your Tank

The ‘wen’ or growth on the top of a Ranchu Goldfish’s head is delicate and can be prone to infection. When setting up a Ranchu tank, avoid sharp objects on which your fish can hurt the wen. That means ornamental toys or pieces of driftwood are a no for these fish – but beautiful tanks can still be created with aquatic plants, instead.

Specifications

Basic Setup:

• Ideal size: A minimum 20-gallon tank is ideal for a single adult lionhead ranchu goldfish. However, a larger tank of 30 gallons will ideally boost your fish’s well-being. For each fish you wish to add, increase the size by 5-10 gallons. Maximizing the surface area also ensures your goldfish get plenty of oxygen.
• Suitable substrates: As these fish are delicate, the best substrate is one on which they can’t hurt themselves. Both sand and/or larger pebbles are great options. Gravel can work, but choose pieces large enough to avoid your fish choking.

To include live plants, a substrate underneath the gravel or pebbles for them to root can also help support the water quality of your tank, which helps with the Ranchu’s more sensitive physiology.

Specific Parameters:

• Filtration Systems: Filters shouldn’t be too fast but should be sufficient to ensure the tank is kept clean. Choose one that works at a gal/h rate of a minimum of 4 times the amount of water. For example, in a 20-gallon tank, you would have an 80 gal/h rate filter. A filter that is too fast can make it harder for the slow-swimming Ranchu to move around.
• Ammonia and nitrites: never allow ammonia to rise above zero. Nitrites are also ideally zero, so test as with any fish, remembering these fish are less tolerant of buildup.
• pH Level: 7-8. Likewise, test as you would with any fish.
• Water hardness: 5-20 dGH.
• Temperature: 65-72 Fahrenheit or 18-22 degrees Celsius. A tank thermometer is useful as Ranchu Goldfish won’t tolerate the kind of temperature fluctuations that hardier Goldfish can manage.
• Lighting: An LED light is perfect for Ranchu and helps maintain a day/night cycle ideally of 6-8 hours of light. This balances your fish’s circadian rhythm and prevents your fish from losing color as it ages.
• Tank Maintenance: As with other goldfish, it’s best to change the water in your Ranchu tank once per week, removing approximately ¼ – ⅓ of the water and replacing it with fresh.

Tank Environment, Aquatic Plants, And Tankmates

1. Best Plants For a Ranchu Goldfish Tank

Ranchu Goldfish like to eat plants! However, you can choose fast-growing plants so that your fish can’t destroy them. Another good option is to go for mosses and other plants that attach to logs and bits of wood. This way, your goldfish can’t dig them up.

Suitable fast-growing plants:

• Cabomba species (also known as fanwort)
• Elodea species
• Hornwort (Ceratophyllum), which has the added benefit of helping remove nitrates

Popular beginner mosses and other plants that attach to wood or stones: 

• Java moss (vesicularia dubyana)
• Java fern (leptochilus pteropus)
• Anubias species

2. Best Lionhead Ranchu Goldfish Companions:

The best companions for your new pet are other lionhead ranchu goldfish or related lionhead goldfish. They also work well with similar fancy fish such as orandas or bubble eyes. Goldfish varieties that swim fast, such as the Comet Goldfish, will, unfortunately, outcompete your Ranchu for food, and are best to avoid.

If you want to keep things simple, a single-species group of these fish is still captivating. You can keep them all one color or include fancy or black ranchu goldfish too.

Despite their slow speed, Ranchu can chase and eat small invertebrates such as shrimp. If you wish to add invertebrates, large snails are a safer choice and have the added benefit of keeping the tank free from algae.

Selecting Your Fish

Genuine Ranchu are rare. In addition, this is a breed that can suffer from overbreeding. Unusual colors such as black, gold, or bicolor, are even rarer. Want to know if you have found a true Ranchu Goldfish as opposed to a regular lionhead? Below is a list of characteristics that distinguish the typical Ranchu:

• A symmetrical, fan-shaped tail often likened to flowers
• An egg-shaped body. This tends to be slightly longer than it was in the past, which improves your fish’s health
• A broad, rectangular head, which gives it its other name of ‘buffalo head goldfish’.
• Smooth back without any traces of a dorsal fin, another factor that gives it its cute appearance.

How To Tell Ranchu Goldfish Apart

Ranchu are sometimes mistaken for other lionhead goldfish. In fact, breeders may accidentally sell these lionheads in place of true Ranchu. Things get even more confusing as true Ranchu can be called ‘lionhead Ranchu Goldfish’ too.

To identify Ranchu Goldfish, check the body length (Ranchu have longer bodies whereas other lionheads are more strikingly egg-shaped), as well as the head and shape of wen growth.

A true Ranchu has a rectangular wen that starts from the gills. The wen of a regular lionhead goldfish is much more rounded and this is easier to spot when viewed from above. Ranchu tails also hang at a 45 degree angle.

Lionhead goldfish tails are showier and flare more. Check also for a distinctive shoulder hump – the Ranchu has one, whereas the shoulder area of the lionhead is flatter.

Color Variants and Patterns

The Ranchu can be categorized into Japanese (selected for top-down viewing in contests) or Chinese and Thai ranchu (both selected for side-on view).

Otherwise, different color variations available include:

• Red Ranchu, the most common
• Red and white Ranchu, which includes many of the specific Japanese patterns
• The black ranchu goldfish, which is very rare
• Blue ranchu goldfish, which has a silvery tint
• Fancy Ranchu Goldfish (such as bi-colored or calico)

Some calico or black ranchu goldfish also have pearlescent, or nacreous scales. In addition, black Ranchu Goldfish can come in rare yet stunning bi-color variants such as black and orange.

Feeding Your New Companions

Feeding any fish a good quality diet is important. These are omnivorous fish, so a varied diet also includes protein, pellets, and vegetable matter. Sometimes if fish are bored with the food, they may stop eating. However, this can also be a sign of a more serious disease. Read on for tips on the best way to feed your fish a varied diet.

Pellets: pellets are a good staple food for any goldfish, however, feeding a broader range of food is crucial to provide resilience against disease.

Plants: Goldfish in the wild are naturally omnivorous and will eat bits of plant matter and even leaves that fall onto the surface of their habitat. You can mimic this with vegetables, such as:

• Half a shelled pea
• Broccoli
• Lettuce
• Cauliflower
• Very small pieces of sweet potato and/or plantain

Protein: Good protein sources include daphnia, or water fleas, as well as tubifex worms, glass worms, and brine shrimps. You should remove any uneaten live food after the feeding period to prevent the spread of parasites. Did you know, protein contributes to the growth of the wen in all lionhead ranchu goldfish and related varieties. However, don’t feed too much or this can cause overgrowth.

Temperament And Behaviour

The Ranchu Goldfish has a curious personality and tends to be happiest in groups. These are gentle, slow-moving fish. Nevertheless, they have tons of charm and enjoy exploring their habitat. This is just one reason to keep it enriched with lots of plants. Like with any fish, a happy Ranchu is a healthy Ranchu.

Ranchu Goldfish swim slowly. In fact, they wiggle as they move their bodies from side to side. For many pet owners, this adds to their charm, but it also means they can’t get around quickly.

Nevertheless, the Ranchu will often swim up to the glass, especially when they know that it’s feeding time. When healthy and calm, they generally respond to outside activity with curiosity.

Ranchu Goldfish Pests And Diseases

Ranchu Goldfish can be slightly more susceptible to disease than hardier goldfish (flat-bodied goldfish). However, if you learn how to spot illnesses, and treat them early, you can keep your pet in tip-top health.

1. Swim Bladder Disease

Symptoms: the fish has trouble keeping a stable position in the water. This disease affects the swim bladder, which is an organ used to stay afloat. Fish may sink, float, or turn upside down. These are common signs that your fish is dying in general, so it’s always good to check them out.

Treatment: Swim bladder disease is normally triggered by bacterial infection of the gas/swim bladder due to poor water quality. Isolate your fish in a separate tank with fresh water ensuring all parameters are kept ideal (nitrates, pH etc), and treat with a course of antibiotics.

2. Fin Rot

Symptoms: Discolouration to fins, which look as if bits are missing to them. This is normally caused by poor tank conditions. In bad cases, the fins may have red streaks or white edges to the rotten parts.

Treatment:  Isolate the fish and keep the parameters ideal. Use an antibacterial treatment in the water if the infection doesn’t clear up over a few days.

3. Ich/White Spot Disease

Symptoms: This disease is most visible on black ranchu goldfish, and is characterized by white spots near the gills and fins. The fish loses interest in the world and seems lethargic. It may rub against objects, as well. This disease is transmissible, so a quick response is important.

Treatment: Isolate the fish as with other diseases. Ich is a protozoan parasite, so antibacterial treatments won’t work, but aquarium salts and other medications can. You can also control the parasite’s life cycle by changing the water daily and rotating fish to a fresh tank every 5-7 days.

Wen Overgrowth

All lionhead ranchu goldfish have a distinctive ‘hood’, or wen, on their head. Occasionally, this grows excessively, making it hard for the fish to see. It also makes it difficult for them to feed and interact with other fish.

Some experts clip the wen themselves in the case of overgrowth. However, it’s best to consult a specialist vet, especially if you are a beginner fish keeper. Always remember that an overgrown wen can more easily become infected.

How To Breed Your Ranchu Goldfish

One of the best ways to encourage your Ranchu Goldfish to breed is by mimicking their natural spawning conditions. The quick guide below will show you how:

Preparing to Breed

• Get everything prepared first, and separate the male and female to encourage spawning. You will also need a spawning mat or mop, and another tank in which to put the goldfish afterwards. This is because goldfish eat their eggs and occasionally fry, so it’s wise to remove them after eggs are laid.
• Reduce the temperature of the tank to about 16 degrees Celsius. This mimics the winter period before the water warms and spring arrives, signaling for the fish to reproduce.
• Gradually raise the temperature up to 20-23 degrees Celsius.
• Ensure that you can see small white growths on the gills of the male. They are called tubercles, will help you tell the sexes apart, and indicate readiness to spawn. When waiting to breed, change water more frequently – once per day is ideal.

Breeding and Caring for Fry

• As fish are spawning, the male will chase the female around the tank until she releases eggs. At this point, he then fertilizes them. Some breeders use a breeding mop that mimics the sheltered environments fish like for spawning.
• Remove the goldfish from the tank at this point, otherwise, they will eat the eggs.
• Keep the eggs safe and secure until the fry hatch. This takes about 4-5 days. Ensure regular water changes and aquarium maintenance as usual.
• Feed the fry on a specialist fry food. They don’t have mouths during the first four days after hatching or so, during which they go through a separate phase of growth outside the egg. Some fishkeepers feed them brine shrimp larvae/fry in the early days after hatching as these are small enough and provide a boost of protein for the growing fish.

Final Thoughts

Ranchu Goldfish are one of the most rewarding freshwater fish you can keep; they no doubt earn their nickname as the ‘king of goldfish’. Their quiet yet playful personalities and striking looks mean that they rarely fail to draw attention.

Although they aren’t the hardest or easiest to take care of, they offer an exciting new world for both beginners ready for the next level and experienced aquarists. Owning a Ranchu is like owning a piece of history – from Edo-era Japan to now, these fish are an old and much-loved breed that have popped up in ukiyo-e art and beyond.

Frequently Asked Questions