Your Essential Guide to Fantail Goldfish Care

Fantail goldfish are among the most popular fancy goldfish varieties, loved for their elegant appearance, flowing tails, and charming personalities. While they share many traits with standard goldfish, they also have unique needs and characteristics.

Whether you're a beginner aquarist or an experienced fish keeper looking to dive into the world of fancy goldfish, this guide will cover everything you need to know about keeping fantail goldfish happy and healthy.

What is a Fantail Goldfish?

Fantail goldfish are a type of fancy goldfish known for their double (or split) tail fin, which resembles a fan—hence the name. Unlike the standard (or common) goldfish, which has a single, streamlined tail and a more torpedo-like body shape, fantails have a rounder, more egg-shaped body and slower swimming habits.

Key Differences from Standard Goldfish:

Body Shape: Fantails are rounder and more compact.
Tail: Fantails have a distinctive double tail; standard goldfish have a single tail.
Swimming Speed: Fantails are slower swimmers due to their body shape and fin structure.
Care Needs: Fantails require more specialised care than common goldfish, particularly in terms of tank setup and water quality. Fantail goldfish are NOT suitable for ponds.

If you would like more information on keeping Goldfish in ponds [Click here] for tips on pond size, feeding and general care!

Varieties of Fantail Goldfish

While "fantail" can refer to the basic double-tailed goldfish, many fancy goldfish breeds fall under this umbrella term. Here are some of the most popular fantail varieties:

1. Oranda

Orandas are famous for the wen—a fleshy growth on top of their heads. They have graceful flowing tails and come in many colours, including red, orange, white, and even blue or black.

2. Ryukin

Ryukin goldfish have a prominent hump behind their head, giving them a striking silhouette. Their tails are long and flowing, and they are very hardy, making them a favourite among fancy goldfish keepers.

3. Ranchu

Often called the "king of goldfish" in Japan, Ranchus have a rounded back and no dorsal fin, giving them a unique and adorable waddle-like swimming motion. Like Orandas, Ranchus can also develop a wen.

4. Telescopic Goldfish (e.g., Black Moor)

Telescopic goldfish are known for their bulging, protruding eyes, which give them a dramatic appearance. The most famous variety is the Black Moor, loved for its deep black coloration and velvety finish.

5. Fantail (Standard Fancy)

The traditional fantail goldfish is the simplest form of fancy goldfish, with a symmetrical double tail and no head growth. It’s a great starting point for those new to fancy goldfish keeping.

6. Bubble Eye Goldfish

The Bubble Eye goldfish is perhaps the most unusual looking of all goldfish breeds. It has no dorsal fin and features fluid-filled sacs (bubbles) under its eyes that grow larger as the fish matures.

Special Care Tips for Delicate Fantail Varieties

Some fantail varieties—such as Bubble Eyes and Ranchus—are more delicate than standard fantails and may struggle in tanks with strong water flow. If you're considering keeping these sensitive types, here are some important factors to keep in mind:

Use soft substrate and smooth décor to prevent injury to sensitive eyes and fins.
Use sponge or low-flow filters to maintain gentle water movement and reduce stress on your fish.
Choose slow, peaceful tankmates—ideally other delicate fancy goldfish.
Avoid fast or aggressive fish that may outcompete them for food.
Spot-feed or hand-feed if needed to ensure they get enough nutrition.

This is by no means a complete list—there are many unique varieties of fantail goldfish, such as Veiltails, Pearlscales, Pompons, and Lionheads. Each type has its own characteristics and care considerations. Make sure to research the specific variety you're interested in, and take note of any special care they may require to keep them healthy and thriving.

Best Practices for Keeping Fantail Goldfish

Fantail goldfish can thrive and live for many years—often well over a decade—when provided with proper care. Here's how to create an ideal environment for them:

1. Tank Size

Make sure your tank can accommodate the full adult size of these fish. Pet store goldfish are usually juveniles and may appear small, but they can grow significantly larger. When stocking your tank, plan for their adult size to ensure they have enough space to grow and thrive long term.

Fancy goldfish can grow quite large—typically 6 to 8 inches long, not including their flowing tails—so they need plenty of space and a stable environment. As a general guideline, allow at least 50 litres for the first fish, and an additional 25 litres for each extra fish. However, this is a minimum, larger tanks are always better, especially if you're planning to keep a group.

Avoid bowls or small tanks entirely—despite outdated practices, they are not suitable for goldfish. Limited space leads to poor water quality, stunted growth, and long-term health issues.

Fantail goldfish, in particular, thrive in long tanks rather than tall ones, as their rounded bodies and slow swimming style require ample horizontal space to move comfortably and grow properly.

Explore our full range of larger aquariums here ,to find the perfect setup for you and your fish

2. Filtration

All Goldfish require filtration; Goldfish are notoriously messy and produce a large amount of thick waste, making strong filtration absolutely essential. Choose a filter with substantial mechanical filtration, such as thick sponge media, to effectively capture and break down their heavy waste so it can be properly processed by the system.

Use both mechanical and biological filtration – Mechanical filtration removes solid debris, while biological filtration helps manage the tank’s bio load by breaking down harmful ammonia and nitrites. You may also want to add filter floss and activated carbon (if not already included) to help trap fine particles and improve water clarity.

Perform weekly water changes (10–25%) to maintain good water quality. Use a gravel siphon during water changes to thoroughly clean the substrate and remove any built-up detritus from the bottom of the tank. Always add in some Tap Safe Solution when topping the tank back up to ensure it is safe for the fish

[Click Here] to check out our aquarium filter buying guide for tips on choosing the right filter and to learn more about how filters support a healthy aquarium environment.

3. Oxygenation

Fantail Goldfish thrive in well-oxygenated water. While many aquarium filters provide some oxygen through surface agitation, it's important to ensure there is adequate surface movement to allow for proper gas exchange.

One of the most effective ways to increase oxygen levels is by adding an air pump to your setup. An air pump sits outside the tank and pushes air through airline tubing connected to an air stone placed in the aquarium. This produces a stream of bubbles that improves water movement and oxygenation.

Keep in mind: The larger your tank or the more goldfish you keep, the higher the oxygen demand will be.

Warm water holds less oxygen, so during warmer months or if your tank runs on the higher end of the goldfish temperature range, extra aeration becomes even more important. Adding an air pump is a simple but effective way to create a healthier environment for your fish.

Benefits of Using an Air Pump in Your Aquarium:

Improved oxygen levels to support fish health and activity
Enhanced gas exchange at the water surface
Better water circulation, helping prevent dead spots in the tank
Supports beneficial bacteria in the filter and substrate by maintaining oxygen-rich water
Reduces risk of low oxygen levels during warmer weather or overnight when plants stop producing oxygen
Emergency Backup - If your filter fails, an air pump can help maintain oxygen levels, giving you valuable time to replace or repair the filter. It’s a simple way to protect your fish during unexpected equipment issues.

4. Water Quality

We have a detailed blog dedicated to understanding your aquarium water parameters – you can read it here.

Maintaining the right water parameters is essential for the health of your fish. Sudden changes or poor water quality can be harmful to any fish, and Fantail goldfish are no exception. While they are relatively hardy, they still thrive best in stable, clean water conditions.

Here are the ideal parameters to aim for:

Temperature: 15–24°C – avoid sudden fluctuations
pH: 7.0–8.0
Ammonia/Nitrite: 0 ppm
Nitrate: Less than 40 ppm
KH (Carbonate Hardness): 80–120 ppm
GH (General Hardness): 80–120 ppm

Use a high-quality water test kit to monitor these levels regularly. We recommend the NT Labs Aquarium Test Kit for accurate and dependable results. By testing your water routinely, you can catch and correct any issues early—before they negatively affect your fish.

5. Feeding Fantail Goldfish: Diet and Portion Guidelines

Due to their rounded body shape, Fantail goldfish are best fed a pellet-based diet. The compact form of their body puts them at a higher risk of swim bladder issues, especially when they ingest food that expands or traps air.

Pellets sink more quickly than flakes, helping to reduce the risk of buoyancy problems and digestive stress. While flake food can be offered occasionally, it’s not ideal as a staple.

Pellets are typically:

More nutritionally dense
Easier for Fantails to eat whole
Less likely to go uneaten and foul the water

Feeding Amounts:

Juvenile Fantails: Typically require 2–3 small pellets once daily
As your fish grows, gradually increase the quantity or switch to a larger pellet size to match their nutritional needs and mouth size
Avoid overfeeding—Fantails are prone to digestive issues, and excess food can quickly degrade water quality if left uneaten

Treat Foods:

You can supplement their diet with occasional treats, which add variety and enrichment. Suitable options include:

Frozen or live foods such as bloodworms, brine shrimp, and mysis shrimp
Treat tablets that can be stuck to the front of the glass for interactive feeding

We recommend offering treat foods no more than 2–3 times per week to maintain a balanced diet and avoid digestive upsets.

6. How Many Fish Per Tank?

There’s no strict rule for stocking levels when it comes to Fantail goldfish, but as a general guideline for adult-sized fish, we recommend the following:

1 Fantail per 50 litres of water
Add an additional 25 litres for each extra Fantail

Example: A 100-litre tank can comfortably accommodate three adult Fantail Goldfish—as long as it is supported by adequate filtration.

Although Fantails often start out quite small, it can be tempting to fill the tank with multiple juveniles. However, they grow quickly, and overcrowding can become a serious issue if they’re kept in an undersized aquarium. Overcrowded tanks can lead to poor water quality, increased stress, and a higher risk of disease.

It’s best to plan for your fish’s long-term needs—either by choosing a tank large enough for them to grow into or by being prepared to upgrade the aquarium as they mature.

7. Tank Mates

Fantail goldfish are peaceful, slow-moving fish that can easily be outcompeted for food, especially in a community tank. Because of their rounded bodies and flowing fins, they aren't strong swimmers and may struggle to keep up with more active or aggressive species. For this reason, it's important to choose tank mates that share similar temperaments and environmental needs.

Recommended Tank Mates:

Other Fancy Goldfish – Such as Oranda, Ryukin, and Ranchu. These varieties have similar swimming abilities and care requirements, making them ideal companions.
Peaceful Bottom Dwellers – Species such as Bristlenose Plecos and Weather Loaches can make good tank mates for Fantails, as they are generally peaceful and tend to keep to themselves. They also feed at different levels of the tank, so competition for food is minimal. However, keep in mind that these fish can grow quite large and produce significant amounts of waste—similar to Fantails—so this should be considered when planning your tank size and stocking levels.
Snails – Such as Mystery Snails or Ramshorn Snails, which can help keep algae in check without disturbing the goldfish.

Tank Mates to Avoid:

Common Goldfish, Comets, and Shubunkins – These types are much faster and more agile. They tend to dominate feeding times and can unintentionally stress or injure slower fish like Fantails.
Tropical Fish – Most tropical species require higher water temperatures than Fantails can tolerate. Additionally, some tropical fish can be fin-nippers or aggressive toward slower tankmates.
Pond Fish – Avoid keeping species such as Koi, Orfe, Tench, and similar pond-dwelling fish in an indoor aquarium. These fish grow very large and will quickly outgrow a typical home tank. They are also much faster and more assertive than Fantails, often outcompeting them for food and potentially bullying them, which can lead to stress, injury, or even death

Introducing New Tank Mates: Important Considerations

When adding new fish to your aquarium, it’s essential to monitor them closely, especially during the first few weeks, to ensure a smooth and safe integration. Even species known to be peaceful can show unexpected behaviours when adapting to a new environment.

Here are some key tips to keep in mind:

Observe Behaviour Closely
Watch for signs of aggression, bullying, excessive hiding, or stress. If any fish appears to be harassing others or struggling to adapt, you may need to separate them.
Ensure Dietary Needs Are Met
Different species often have different dietary requirements. For example:

Plecos and other bottom dwellers need sinking pellets or algae wafers.
Fantails and most goldfish prefer floating or slowly sinking food.

Make sure each fish is receiving the appropriate type of food for their species and feeding habits.

Avoid Overfeeding
Overfeeding can quickly lead to poor water quality and health issues. Feed small amounts, ensuring that all fish have access to food without excess left to decay in the tank.
Monitor for Uneaten Food
Check that each fish is actually eating. Slower or more timid fish may struggle to compete during feeding time and may need food targeted specifically to their area of the tank.
Adjust Feeding Strategy if Needed
If you notice some fish consistently missing out or others dominating the food, consider feeding in multiple spots or using feeding tools to ensure fair distribution.

Careful observation and a little extra planning during the early stages can help prevent problems and create a peaceful, balanced tank environment.

8. Common Health Issues in Fantail Goldfish

Fantail goldfish are generally hardy and well-suited to home aquariums, but they can still develop health issues—especially if water quality, diet, or tank conditions are not properly maintained. Below are some of the most common problems, along with their symptoms and treatments.

1. Swim Bladder Disorder

Symptoms:

Difficulty swimming upright
Floating on one side or sinking to the bottom
Struggling to maintain balance or hovering upside-down

Causes:

Overfeeding
Poor diet (low in fibre)
Constipation
Rapid swallowing of air while feeding

Treatment:

Fast the fish for 24–48 hours
Feed deshelled peas (boiled and chopped) to relieve constipation
Switch to a sinking pellet diet to reduce air intake
Improve water quality and ensure stable temperature- NT Labs Swimbladder Treatment can also be added to aid in recovery.

2. White Spot (Ich)

Symptoms:

Tiny white spots on the body, fins, or gills
Scratching or rubbing against tank surfaces
Rapid gill movement or signs of distress

Causes:

Parasitic infection (Ichthyophthirius multifiliis)
Often triggered by stress or sudden temperature changes

Treatment:

Raise the water temperature gradually to 26–28°C to speed up the parasite’s lifecycle
Use an over-the-counter Ich treatment (e.g. NT Labs Anti-White Spot or eSHa Exit)
Maintain high oxygen levels during treatment
Remove carbon from your filter before adding medication

3. Internal Parasites / Worms

Symptoms:

Weight loss despite regular feeding
Stringy or white faeces
Lethargy or reduced appetite

Causes:

Contaminated live or frozen food
Infected new fish added to the tank without quarantine

Treatment:

Use a medicated anti-parasitic treatment (e.g. NT Labs Ant-Fluke & Wormer)
Offer only pellet food during treatment period and increase offering to twice daily
Disinfect nets and tank equipment to prevent spreading

4. Bacterial Infections / Fin Rot

Symptoms:

Frayed or ragged fins
Red streaks in fins or body
Open sores, ulcers, or cloudy patches

Causes:

Poor water quality
Physical injury
Stress or a weakened immune system

Treatment:

Improve water quality with testing and regular weekly water changes
Use aquarium-safe antibacterial treatments (e.g. eSHa Gastrobac or API Melafix)
Remove any sharp decorations that could cause injury
Quarantine or isolate if the infection is severe – If removing the fish isn’t possible, consider placing it in a hatchery net within the same tank to reduce stress and prevent further spread of infection

5. Dropsy

Symptoms:

Severe bloating
Pinecone-like appearance (scales sticking out)
Lethargy, loss of appetite

Causes:

Internal bacterial infection
Organ failure, usually due to long-term poor conditions

Treatment:

Isolate the affected fish immediately
Treat with broad-spectrum antibacterial medications (eSHa 2000 or NT Labs Anti Internal Bacteria Treatment)
Add aquarium-safe tonic salts directly to the tank to help reduce swelling or provide the fish with a salt bath twice a week. Always follow the dosage instructions provided on the product packaging.
Unfortunately, dropsy is often fatal if not caught early

Preventing Health Problems

We strongly believe that prevention is better than cure. In most cases, maintaining good water quality, a balanced diet, and proper care will help your fish thrive and avoid health issues altogether. However, if problems do occur, fish kept in healthy conditions generally have a much better chance of recovering with appropriate treatment.

Some top tips for prevention include:

Maintain excellent water quality (test weekly)
Feed a balanced, species-appropriate diet
Perform regular water changes (10–25% weekly)
Quarantine new fish before adding them to your main tank
Monitor fish daily for signs of illness or behaviour changes

Need Help Identifying a Fish Health Issue?

If you're unsure what's wrong with your fish, feel free to send us photos or videos at info@completekoi.com. Our team will do their best to help identify the issue and recommend an appropriate treatment plan.

Alternatively, if you're local to our store, we offer an in-person health check service, which includes a parasite scrape (viewed under a microscope) , physical assessment of your fish and a water test service. This is the most accurate way to diagnose parasites and ensure the correct treatment is used.

Final Thoughts

Fantail goldfish are truly delightful pets, full of charm and personality. Their elegant swimming and unique appearance make them fascinating to watch and a wonderful addition to any home. However, they thrive best when given thoughtful care and a properly maintained environment. Providing a spacious tank, effective filtration, regular upkeep, and compatible tank mates is essential for their health and happiness.

If you’re considering starting a goldfish aquarium, now is the perfect time to take the plunge! Begin with careful research and planning to set up the ideal habitat for your fantails. Start slow, stay patient, and commit to consistent care—your efforts will be rewarded with years of enjoyment and companionship from these beautiful fish.

Ready to bring fantail goldfish into your life?

Take the first step today by gathering the right equipment, learning about their needs, and preparing your tank for a healthy, thriving aquatic community. Your fish—and your future self—will thank you!

For more tips and information on aquarium care and fish keeping, explore the rest of our blogs here...

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