Pet Aqua — Three Step Guide to Healthy Goldfish

Carassius auratus · Fancy and Single-Finned Varieties

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Pet Aqua — 3-Step Guide to Happy, Healthy Goldfish Keeping

1Set Up

2Add Goldfish

3Maintain

STEP 1

Set Up Your Goldfish Tank

Goldfish are one of the most popular pet fish in the world, but they are often misunderstood. They are not bowl fish. They grow large, produce a lot of waste, and need properly filtered, well-oxygenated water. Getting the setup right from day one prevents most problems. The tank must be fully cycled before any goldfish go in. Take your time — there are no shortcuts.

The Two Categories of Goldfish

Before you set up a tank, you need to understand which type of goldfish you want to keep. Goldfish fall into two main categories, and they have very different space requirements:

Fancy goldfish — have round, egg-shaped bodies and double (split) tails. They are slower swimmers and stay smaller. These are the goldfish suited to aquariums. Minimum 60 litres per fish.
Single-finned goldfish — have slim, streamlined bodies and single tails. They are fast swimmers, grow very large, and produce a huge amount of waste. These are best kept in ponds or very large aquariums.

Never mix fancy and single-finned goldfish in the same tank. The single-finned fish are faster and will outcompete the fancies for food, and their boisterous swimming will stress the slower fancy varieties.

Tank Size — Fancy Goldfish: 60 Litres Per Fish

At Pet Aqua, we recommend a minimum of 60 litres per fancy goldfish. Goldfish produce a significant amount of waste for their size, and larger water volumes mean more stable water parameters. Fancy goldfish stay smaller than single-finned varieties, but they still need real space — not a bowl.

Minimum 60 litres for the first fancy goldfish.
Add 60 litres for each additional fancy goldfish. Two fancy goldfish need a 120-litre tank, three need 180 litres.
A larger tank is always better. More water volume dilutes toxins and buffers temperature swings.
Choose a long, wide tank over a tall one. Goldfish are bottom-dwellers that benefit from floor space and swimming length.
Avoid tanks under 60 litres for goldfish. Small volumes swing in water quality too fast, which stresses the fish and causes illness.
Never keep goldfish in a bowl. Bowls stunt growth, cause ammonia poisoning, and shorten lifespans dramatically. A goldfish can live 10 to 15 years or more in a proper tank — in a bowl, it will die within months.

Single-Finned Goldfish — Ponds or Very Large Aquariums

Single-finned goldfish (common, comet, and shubunkin) are a different story. They grow much larger than fancy goldfish — often 25 to 30cm or more — and they are fast, powerful swimmers that produce an enormous amount of waste. These are pond fish at heart.

Single-finned goldfish are best kept in outdoor ponds or very large aquariums.
A single common, comet, or shubunkin needs an absolute minimum of 200 litres in an aquarium, with 100 litres for each additional fish. In practice, a much larger tank is needed for long-term health.
A garden pond is the ideal home for adult single-finned goldfish. A minimum pond size of 400 litres is recommended for a small group.
These fish grow quickly and can reach over 30cm in length. Most home aquariums cannot accommodate them long-term.
If you start with single-finned goldfish in an aquarium, be prepared to upgrade to a pond or very large tank as they grow. Many experienced keepers move single-tail goldfish outside once they outgrow their aquarium.
Do not buy single-finned goldfish for a small tank. They will outgrow it and suffer.

Where to Place Your Goldfish Tank

Choose the position carefully. A full goldfish tank is heavy and hard to move once set up.

Place away from windows. Direct sunlight causes algae problems and temperature swings.
Keep away from radiators, heaters, and air conditioning vents. Goldfish prefer cooler water, but stability still matters.
Avoid busy walkways and areas with vibrations.
Use a dedicated stand or solid furniture rated for the weight. A 120-litre tank weighs over 120kg when full.
Ensure the surface is level. An uneven stand can crack the glass.
Keep near a power point for the filter and light. Use a drip loop on cables for safety.

Filtration — Goldfish Produce a Lot of Waste

Goldfish are heavy waste producers. A strong biological filter is essential — it is not optional. The filter processes fish waste (ammonia) into less harmful compounds. Without a filter, ammonia builds up rapidly and kills the fish.

Use a filter rated for a tank larger than yours. Goldfish produce more waste than most fish of similar size, so oversize the filter.
A canister filter or a large hang-on-back filter is ideal for goldfish tanks. Sponge filters work for smaller setups but may struggle with the bioload of multiple goldfish.
Fancy goldfish prefer a gentle current. If the filter flow is too strong, use a spray bar or baffle the output. Single-finned goldfish can handle stronger flow.
Run the filter continuously. It should never be switched off for more than 2 to 3 hours.
The filter holds the beneficial bacteria that keep your goldfish alive. Never replace all the media at once.
Consider adding an air stone for extra oxygenation. Goldfish benefit from well-oxygenated water, especially in warmer months.

Heating — Goldfish Are Cool-Water Fish

Goldfish are cool-water fish, not tropical. In most UK homes, they do not need a heater. They prefer temperatures between 18 and 24 degrees C, which is around normal room temperature. However, stability matters — sudden temperature swings are harmful.

Ideal temperature for fancy goldfish: 18 to 22 degrees C.
Single-finned goldfish tolerate a wider range: 10 to 24 degrees C.
In most UK homes, no heater is needed. Room temperature will keep the tank in range for much of the year.
Avoid placing the tank near radiators or in direct sunlight, which can cause dangerous temperature spikes.
In very cold rooms (below 10 degrees C), the goldfish will slow down and eat less. This is not dangerous, but monitor the temperature.
Do not exceed 24 degrees C for extended periods. Warm water holds less oxygen and increases the fish's metabolism, causing them to eat more and produce more waste.
Use a thermometer to monitor the temperature. Stability is more important than hitting an exact number.

Substrate and Decor

Use smooth sand or rounded gravel. Goldfish spend time foraging on the bottom and will suck up substrate. If using gravel, choose pieces that are either very small (fine sand, under 1mm) or too large to swallow. Avoid medium-sized gravel that can be swallowed and cause impaction.
Wash the substrate thoroughly before it goes in the tank.
Do not use soap or detergents. Residue kills fish.
Choose decor with no sharp edges. Fancy goldfish with telescope eyes or delicate fins can injure themselves on sharp ornaments.
Live plants can be used, but goldfish will eat or uproot them. Hardy plants like Java fern, Anubias, and Marimo moss balls are the best choices. Attach plants to rocks or wood rather than planting in the substrate.
Provide hiding spots with smooth rocks or ceramic caves, but leave plenty of open swimming space.

Lid and Water Level

Goldfish are not strong jumpers, but a lid is still recommended.

Use a lid to prevent escape and reduce evaporation. A lid also helps keep dust and contaminants out of the tank.
Ensure the lid is well-fitted but allows for gas exchange at the surface.

Water Parameters

Goldfish are hardy and tolerate a wide range of water parameters, but they need excellent water quality due to their high waste production. Stability matters more than hitting a perfect number. Most UK tap water falls in the acceptable range.

Parameter	Ideal Range	Tolerance	Notes
Temperature	18 to 22 degrees C (fancy)	10 to 24 degrees C	Stability is critical. Avoid sudden swings
pH	7.0 to 7.5	6.5 to 8.0	Stability more important than exact value
Hardness	5 to 19 dGH	5 to 20 dGH	Flexible — tolerates most UK tap water
Ammonia	0 ppm	0 ppm	Zero tolerance — cycle tank fully before adding goldfish
Nitrite	0 ppm	0 ppm	Zero tolerance — toxic to goldfish
Nitrate	Below 20 ppm	Below 40 ppm	Goldfish produce a lot of waste — regular water changes essential
Chlorine	0 ppm	0 ppm	Always treat tap water with a dechlorinator

Parameter ranges based on guidance from OATA, PetMD, Aqueon, Aquarium Co-Op, and Chewy.

The Cycle — Do Not Skip This

At Pet Aqua, we insist on a fully cycled tank before adding goldfish. This is not optional. Goldfish produce a heavy bioload — they eat a lot and produce a lot of waste. In an uncycled tank, ammonia builds up rapidly and burns the fish's gills. The cycle takes 4 to 6 weeks to complete naturally, or can be sped up with bottled bacteria.

Set up the tank with substrate, decor, filter, and water. Run it with the filter on.
Add Seachem Stability daily for 7 days to introduce beneficial bacteria and start the biological filter.
Add Seachem Prime to make the tap water safe by removing chlorine and chloramine.
Add a small pinch of fish food every 2 to 3 days to produce ammonia and feed the bacteria, or use pure ammonia.
Test the water regularly. You will see ammonia rise, then fall. Then nitrite rises and falls. Then nitrate appears. When ammonia and nitrite both read 0 and nitrate is showing, the tank is cycled.
Do a 20% water change before adding your goldfish to bring nitrates down.
Bring a water sample to Pet Aqua for testing before you buy your goldfish. We will confirm it is safe.

Important Tips for Setup

Never keep goldfish in a bowl. Bowls stunt growth, cause ammonia poisoning, and shorten lifespans. A goldfish can live 10 to 15 years or more in a proper tank.
Never keep single-finned goldfish in a small tank. They grow very large and need a pond or very large aquarium.
Never add goldfish to a tank that has not finished cycling. Ammonia burns their gills.
Never keep goldfish without a filter. They produce too much waste for an unfiltered tank.
Never mix fancy and single-finned goldfish. The single-finned fish will outcompete the fancies for food.
Avoid sharp decor, especially with telescope-eye varieties. Their eyes are delicate and easily injured.

Step 1 Checklist

Tank set up — minimum 60 litres per fancy goldfish, larger is better
Single-finned goldfish planned for a pond or very large aquarium (200 litres plus)
Tank placed away from windows, radiators, and vibrations
Stand rated for the weight, surface level
Filter installed and running — oversized for the bioload
Smooth sand or rounded gravel substrate added
Decor added — no sharp edges, plenty of open swimming space
Lid fitted
Thermometer in place
Seachem Prime added to make tap water safe
Seachem Stability dosed daily for 7 days
Tank fully cycled — ammonia 0, nitrite 0, nitrate showing
Water tested and confirmed safe before buying goldfish

STEP 2

Add Your Goldfish

After the tank is fully cycled, it is ready for your goldfish. Choose the right type for your setup, acclimatise them properly, and get the feeding routine right from day one. Goldfish are omnivores — they need a varied diet, not just flakes.

Types of Fancy Goldfish

Fancy goldfish have round, egg-shaped bodies and double (split) tails. They are slower swimmers and better suited to aquariums than single-finned varieties. They come in a wide range of shapes, colours, and fin types. Some are hardy and beginner-friendly; others need more careful care due to extreme body shapes or delicate features.

Fancy · Beginner

Fantail

The hardiest and most sensible fancy goldfish for beginners. Classic egg-shaped body with a split, fan-like tail. No head growth or telescope eyes. Tolerates mistakes better than any other fancy variety. A great first goldfish.

Fancy · Beginner

Ryukin

Deep body with a characteristic high arched back (hump) that develops as the fish matures. Long flowing double tail. Hardier than most fancies and more active. A good choice for beginners who want something a bit more showy than a fantail.

Fancy · Intermediate

Oranda

One of the most popular fancy goldfish in the world. Egg-shaped body with a fleshy head growth called a "wen" that develops over several years. Long flowing fins. The wen needs clean water to prevent infection. Red cap orandas (red wen, white body) are the most sought-after.

Fancy · Intermediate

Black Moor

A telescope-eye variety with a velvety black body and protruding eyes. Poor eyesight means they struggle to compete for food — keep with other slow-moving fancies only. No sharp decor. The black colour may fade to bronze with age or in warm water — this is normal.

Fancy · Intermediate

Telescope Eye

Same body shape as a fantail but with large protruding eyes. Comes in calico, red-white, and orange varieties. Poor vision means they need gentle tank mates and soft decor. Eyes are delicate and easily injured.

Fancy · Advanced

Ranchu

Japan's classic fancy goldfish. Egg-shaped body with no dorsal fin and a prominent head growth (wen). Requires more careful selection and care due to body balance. A prized show variety. Needs smooth decor and gentle handling.

Fancy · Advanced

Lionhead

Similar to the Ranchu but with a slightly different back profile. No dorsal fin, with a thick head growth. Slow swimmer that needs peaceful tank mates. Advanced care due to body shape and balance.

Fancy · Intermediate

Pearlscale

Round, almost spherical body with pearl-like scales that have a raised, domed centre. Striking appearance but delicate scales. Needs smooth decor and careful handling to avoid scale damage.

Fancy · Advanced

Bubble Eye

One of the most unusual varieties. Large fluid-filled sacs under the eyes that grow as the fish matures. No dorsal fin. Extremely delicate — the bubbles can be ruptured by sharp decor or strong flow. For experienced keepers only.

Which Fancy Goldfish Should You Choose?

Fantails are the best choice for beginners. They are hardy, adaptable, and lack the extreme features that require specialised care.
Ryukins and Orandas are good intermediate choices once you understand filtration and feeding competition.
Black Moors and Telescope Eyes need careful tank setup — no sharp decor, and only keep with other slow-moving fancies.
Ranchus, Lionheads, and Bubble Eyes are for experienced keepers. Their body shapes and delicate features require more careful management.

Types of Single-Finned Goldfish

Single-finned goldfish have slim, streamlined bodies and single tails. They are fast, powerful swimmers that grow very large. These are pond fish at heart and are best kept in outdoor ponds or very large aquariums.

Single Fin · Pond

Common Goldfish

The original goldfish. Slim body, single tail, hardy and long-lived. Grows to 25 to 30cm or more. Best in ponds or very large aquariums (200 litres plus per fish). Not suited to small tanks.

Single Fin · Pond

Comet

Slimmer and longer-tailed than the common. Fast, active swimmer. Grows to 25 to 30cm. Comes in solid red, orange, white, or red-and-white. Best in ponds. Needs 200 litres plus per fish in an aquarium.

Single Fin · Pond

Shubunkin

Calico-patterned single-tail with blue, red, black, white, and yellow patches. Same hardy body type as the common and comet but with the most decorative colouration of the single-tail group. Best in ponds. Needs 200 litres plus per fish in an aquarium.

Important: Single-Finned Goldfish Need Ponds

Single-finned goldfish are best in ponds or very large aquariums. They grow too large for most home tanks.
Minimum 200 litres for a single common, comet, or shubunkin in an aquarium, with 100 litres for each additional fish. In practice, larger is always needed.
A garden pond is the ideal long-term home. Minimum pond size: 400 litres for a small group.
Never keep single-finned goldfish with fancy goldfish. They are faster and will outcompete the fancies for food.

Buying Your Goldfish

Ask at Pet Aqua about the goldfish we have available. Choose active, alert fish with clean fins and bright colour.

Ask at Pet Aqua about goldfish currently available, or visit us in store.
Choose active, alert fish. Healthy goldfish are responsive and swim around when approached.
Check the fins. They should be clean and whole, not torn, clamped, or ragged.
Check the body. Look for clean, bright eyes and smooth scales. Avoid fish with white spots, cotton-like growths, red patches, or bloated bodies.
Check the gills. They should be clean and move steadily. Rapid gill movement can indicate poor water quality or stress.
Buy goldfish of similar size and type. Mixing sizes leads to feeding competition. Mixing fancies with single-finned fish leads to the fancies being outcompeted.
Goldfish are social fish. Keep at least two together where possible — they do better in groups.

Bringing Your Goldfish Home

The journey home and the introduction to the tank are stressful for any fish. Get it right.

Keep the bag insulated — use a cool bag in summer and a wrap in winter. Temperature shock is dangerous.
Do not leave the fish in a hot or cold car. Go straight home.
When you arrive, float the sealed bag in the tank for 15 minutes to equalise the temperature. Do not open the bag yet.
After temperature equalises, open the bag and roll the top down to keep it floating. Add a small amount of tank water to the bag every 2 minutes for 5 to 10 minutes. This slowly acclimatises the goldfish to your water parameters.
After 20 - 25 minutes, use a net to transfer the goldfish into the tank. Do not pour the bag water into the aquarium.
Dispose of the bag water down the sink.
Keep the light off for the first few hours to reduce stress.
Offer a small amount of food the next day. If the fish do not eat, remove the food and try again the following day.

Feeding — A Varied Diet

Goldfish are omnivores. In the wild they eat plants, insects, crustaceans, and detritus. A good goldfish diet is varied — not just flakes. Feed small amounts once or twice a day. Goldfish will eat as much as you give them, so it is up to you to control portions. Overfeeding is one of the most common causes of goldfish illness.

Pet Aqua Made

Pet Aqua Premium Fancy Goldfish Granules

Made in store by Pet Aqua, our premium fancy goldfish granules are formulated specifically for fancy goldfish. They provide a balanced diet with the right protein, carbohydrate, and vitamin content for healthy growth, vibrant colour, and strong immune systems. The granules sink, which suits fancy goldfish that feed from the bottom. Available in store now.

What to Feed

Pet Aqua Premium Fancy Goldfish Granules — the ideal staple food for fancy goldfish. Made in store, these sinking granules are formulated specifically for fancy goldfish nutrition. Feed as the main diet.
Quality goldfish pellets as an alternative or supplement. Ensure they sink or soften quickly — fancy goldfish can take in air when feeding from the surface, which causes buoyancy problems.
Blanched vegetables: courgette (zucchini), shelled peas, broccoli. Boil for 2 to 3 minutes until soft, cool under cold water, then add a small piece. Remove after 24 hours. Peas are particularly good — they act as a natural laxative and help prevent constipation and swim bladder issues.
Frozen or freeze-dried bloodworms and brine shrimp as treats, 1 to 2 times per week. These add protein variety to the diet.
Avoid generic tropical fish flakes as a staple — they are not formulated for goldfish nutrition and can cause digestive problems.

How Much and How Often

Feed once a day. Offer only what the goldfish can consume in 1 to 2 minutes.
A good rule: the amount of food should be roughly the size of the fish's eye per feeding.
Remove uneaten food after 2 to 3 minutes. Anything left will rot and spike ammonia.
Fasting one day per week is beneficial. It lets the digestive system rest and prevents constipation and bloating.
Feed shelled peas once a week as a natural laxative to help prevent swim bladder problems.
Overfeeding is one of the most common causes of goldfish illness. Less is more.

Foods and Products That Harm Goldfish

Overfeeding — the number one cause of goldfish illness. Uneaten food rots, spikes ammonia, and causes bloating and swim bladder problems. Feed small amounts only.
Bread and biscuits — never feed bread or biscuits to goldfish. They cannot digest them and they cause serious digestive problems.
Floating flakes as a staple for fancy goldfish — fancy goldfish take in air when feeding from the surface, which causes swim bladder issues. Use sinking food instead.
Copper-based medications — toxic to goldfish. Always check medication labels.
Air fresheners, aerosols, and cleaning sprays — never spray near the tank. Chemicals drift into the water and are toxic to fish.
Soap and detergents — never wash tank equipment with soap. Residue kills fish.
Sharp decor — tears fins and injures telescope eyes. Use smooth decor only.

Tank Mates

Goldfish are social and do well in groups, but choosing tank mates requires care. The main rule: only keep goldfish with other goldfish of the same type and size.

Keep fancy goldfish with other fancy goldfish of similar size. Do not mix with single-finned goldfish — they are faster and will outcompete the fancies for food.
Keep single-finned goldfish with other single-finned goldfish of similar size.
Do not keep goldfish with tropical fish. Goldfish prefer cooler water, and many tropical fish need warmer temperatures. The temperature requirements are incompatible.
Do not keep goldfish with aggressive or fin-nipping fish. Goldfish are peaceful and will be bullied.
Do not keep goldfish with small fish that could be eaten. Goldfish will eat anything that fits in their mouth.
Snails (such as apple snails or ramshorn snails) can sometimes be kept with goldfish, but large goldfish may eat small snails.
If in doubt, keep goldfish with goldfish only. They are perfectly happy in same-species groups.

Important Tips for Adding Your Goldfish

Never add goldfish to a tank that has not finished cycling. Ammonia burns their gills.
Never mix fancy and single-finned goldfish. The single-finned fish will outcompete the fancies for food.
Never do a large water change right after adding your goldfish. Keep changes small (20 to 25%) and match the temperature.
Never overfeed. Feed only what the goldfish can eat in 1 to 2 minutes.
Never spray aerosols, air fresheners, or cleaning products near the tank.
Never feed bread or biscuits. Goldfish cannot digest them.
Feed Pet Aqua Premium Fancy Goldfish Granules as the staple diet for fancy goldfish.

Step 2 Checklist

Tank fully cycled — ammonia 0, nitrite 0, nitrate showing
Goldfish type chosen — fancy for aquariums, single-finned for ponds or very large tanks
Fancy goldfish: minimum 60 litres per fish
Single-finned goldfish: minimum 200 litres per fish or a pond
Goldfish chosen — active, alert, clean fins, bright eyes
Similar size and type only — no mixing fancies with single-finned
Goldfish acclimatised slowly over 20 to 25 minutes
Bag water disposed of, not added to tank
Light kept off for first few hours
Fed small amount the next day
Pet Aqua Premium Fancy Goldfish Granules as staple diet
Blanched vegetables and peas added for variety
Bloodworms and brine shrimp as treats 1 to 2 times per week
One fasting day per week
Uneaten food removed after 2 to 3 minutes
No aerosols, air fresheners, or cleaning sprays near the tank

STEP 3

Ongoing Maintenance & Health

A simple routine keeps the tank healthy and your goldfish thriving. Consistency matters more than effort. Goldfish are hardy fish when kept in clean, well-filtered, stable water — the problems come from poor water quality, overfeeding, and tanks that are too small.

Water Changes

Regular water changes are the single most important maintenance task. Goldfish produce a heavy bioload — they eat a lot and produce a lot of waste. The filter handles ammonia and nitrite, but nitrate builds up over time and must be removed with water changes.

Change 20 to 30% of the water weekly. Goldfish tanks need more frequent changes than most because of the high waste production.
Never change more than 50% at once unless there is an emergency. Large changes cause parameter swings that stress the fish.
Always match the temperature of the new water to the tank. Use a thermometer — even a few degrees difference can shock a goldfish.
Add Seachem Prime to the new water before it goes in the tank. This removes chlorine and chloramine instantly. Never add untreated tap water.
Match the pH of the new water to the tank. Stability is more important than hitting a perfect number.
Pour the new water in slowly. Do not pour it directly onto the fish or disturb the substrate.
Use a gravel vacuum to siphon waste from the substrate during water changes. Goldfish produce a lot of solid waste that accumulates in the substrate.
If your tap water is chloraminated (common in UK city water), ensure your dechlorinator handles both chlorine and chloramine. Seachem Prime does both.

Filter Maintenance

The filter holds the beneficial bacteria that keep your goldfish alive. Clean it properly or you risk crashing the tank. Goldfish produce a lot of waste, so the filter works hard and needs regular attention.

Never clean the filter media under tap water. Chlorine kills beneficial bacteria. Always rinse the media in a bucket of old tank water removed during a water change.
Squeeze the sponge gently in old tank water to remove debris. Do not scrub or wring it out aggressively.
Do not replace all the filter media at once. Replace media in stages — never more than half at a time — and run old and new together for a month.
Clean the filter every 2 to 4 weeks, or when the flow reduces. Goldfish tanks may need more frequent cleaning due to the high bioload.
After cleaning, add a dose of Seachem Stability to replace any bacteria lost.
Check the filter intake regularly. Goldfish can sometimes injure themselves on uncovered intakes, especially fancy varieties with long fins.

Lighting and Temperature

Keep the aquarium light on for 8 to 10 hours maximum. Use a timer. More than 10 hours promotes algae.
Do not place the tank near windows. Natural light is uncontrolled and causes algae and temperature swings.
Check the temperature daily. Fancy goldfish do best at 18 to 22 degrees C.
Do not let the temperature drop below 10 degrees C or rise above 24 degrees C for extended periods.
Stability is more important than hitting an exact number. Sudden temperature swings stress the fish and weaken the immune system.
In most UK homes, no heater is needed. If the room gets very cold, monitor the temperature and consider insulating the tank.

Regular Water Testing

Test your water weekly. Goldfish produce a heavy bioload, so parameters can shift quickly. Catching problems early prevents illness.

Bring a water sample to Pet Aqua for testing, or use a home test kit.
Test for ammonia, nitrite, nitrate, and pH.
Ammonia and nitrite should always read 0 in a healthy tank. Any reading above 0 is an emergency — do a 25% water change immediately and add Seachem Prime.
Nitrate should stay below 20 ppm. If it rises, increase water change frequency or size. Goldfish produce a lot of waste, so nitrate can climb fast.
Keep a record of your parameters over time. This helps you spot trends before they become problems.

Common Goldfish Health Problems

Swim Bladder Disorder

Symptoms: the goldfish floats upside down, sinks to the bottom, or struggles to maintain its position. Common in fancy goldfish due to their round body shape.
Cause: usually overfeeding, constipation, or taking in air when feeding from the surface. Sometimes caused by poor water quality.
Fix: fast the goldfish for 2 to 3 days, then feed shelled peas (boiled and peeled). Switch to sinking food to prevent air intake. Reduce future portion sizes.

Fin Rot

Symptoms: fins look ragged, torn, or are shrinking back. Often caused by poor water quality or stress.
Fix: test the water immediately, do a 25% water change, and keep the water clean. Clean water alone often cures mild fin rot. Severe cases may need a treatment.

Ich (White Spot Disease)

Symptoms: small white spots appear on the body and fins, like grains of salt. The fish may rub against objects.
Fix: raise the temperature gradually to 24 degrees C and use a white spot treatment safe for goldfish. Remove carbon from the filter during treatment.

Dropsy

Symptoms: the goldfish's body swells and scales stick out like a pinecone. This is usually kidney failure caused by bacterial infection and is often fatal.
Fix: isolate the fish immediately. Treatment is rarely successful. Focus on prevention through clean, well-filtered, stable water.

Ammonia Poisoning

Symptoms: red or bleeding gills, gasping at the surface, lethargy. Caused by high ammonia levels, usually from an uncycled tank, overfeeding, or inadequate filtration.
Fix: test the water immediately. Do a 25% water change and add Seachem Prime. Stop feeding for a day. Check the filter is working properly.

Constipation and Bloating

Symptoms: the goldfish has a swollen belly, struggles to swim normally, or produces stringy faeces. Usually caused by overfeeding or a diet lacking fibre.
Fix: fast for 2 to 3 days, then feed shelled peas. Add blanched vegetables to the regular diet. Reduce portion sizes and add a weekly fasting day.

Wen Infection (Orandas, Ranchus, Lionheads)

Symptoms: the head growth (wen) looks red, inflamed, or has white patches. Caused by poor water quality or bacteria entering the wen tissue.
Fix: test the water, do a water change, and keep the water pristine. The wen is vulnerable to infection when water quality is poor.

Lifespan — Think Before You Buy

Goldfish are a long-term commitment. They can live 10 to 15 years or more with proper care. Some have lived past 30 years. This is not a short-term pet. Before you buy, make sure you are ready to maintain a filtered tank for the full lifespan of the fish.

Goldfish live 10 to 15 years on average. Some live 20 to 30 years with excellent care.
Lifespan depends heavily on water quality, tank size, diet, and temperature stability.
Before you buy, research the care requirements and make sure you can commit to daily feeding, weekly water changes, and ongoing maintenance for the life of the fish.
Set up the tank and cycle it before you bring the goldfish home. Never buy the tank and the fish on the same day.
Single-finned goldfish will likely need a pond as they grow. Be prepared for this before you buy.

Golden Rules of Goldfish Care

Never keep goldfish in a bowl. They need a filtered tank of at least 60 litres per fancy goldfish.
Never keep single-finned goldfish in a small tank. They need a pond or very large aquarium (200 litres plus per fish).
Never mix fancy and single-finned goldfish. The single-finned fish will outcompete the fancies for food.
Never add goldfish to an uncycled tank. Ammonia burns their gills.
Never keep goldfish without a filter. They produce too much waste for an unfiltered tank.
Never overfeed. Feed only what the goldfish can eat in 1 to 2 minutes. Fast one day per week.
Never feed bread or biscuits. Goldfish cannot digest them.
Never feed floating flakes to fancy goldfish as a staple. Use sinking food to prevent swim bladder problems.
Never spray aerosols, air fresheners, or cleaning products near the tank.
Never do a water change larger than 50% unless there is an emergency.
Never clean filter media under tap water. Use old tank water only.
Never keep goldfish with tropical fish. The temperature requirements are incompatible.
Feed Pet Aqua Premium Fancy Goldfish Granules as the staple diet for fancy goldfish.

Step 3 Checklist — Weekly Routine

20 to 30% water change with temperature-matched, dechlorinated water
Seachem Prime added to new water
Temperature checked — 18 to 22 degrees C for fancy goldfish
Water tested — ammonia 0, nitrite 0, nitrate below 20 ppm
Goldfish checked — active, alert, fins clean, eating well
Feeding — Pet Aqua Premium Fancy Goldfish Granules as staple, once daily
Blanched vegetables or peas added for variety
Bloodworms and brine shrimp as treats 1 to 2 times per week
One fasting day per week
Uneaten food removed after 2 to 3 minutes
Filter flow checked — working properly
Substrate siphoned to remove solid waste
Light timer set to 8 to 10 hours

Monthly Routine

Filter media rinsed in old tank water
Substrate deep-cleaned with gravel vacuum
Glass wiped clean
Decor cleaned and repositioned if needed
Plants trimmed if overgrown
Diet reviewed — ensure variety through the month
Goldfish weighed or measured if monitoring growth
Stock the Pet Aqua Premium Fancy Goldfish Granules — available in store

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