Common Goldfish Care Guide
The common goldfish (Carassius auratus) is one of the most well-known coldwater fish in the UK. Often kept in ponds and aquariums, they are hardy, active, and can grow much larger than many people expect.
In this guide, you'll learn everything you need to know about common goldfish care, including tank and pond size, water conditions, compatibility, feeding, and typical UK prices - plus how to buy or sell them locally.
Quick facts about Common Goldfish
Common goldfish are domesticated carp that have been bred for centuries. They are fast-swimming, long-bodied fish and are very different from fancy goldfish varieties.
They are best suited to large aquariums or outdoor ponds due to their size and activity level.
Carassius auratus
20-30 cm (can grow larger in ponds)
East Asia (domesticated species)
120L+ (single fish), pond preferred long-term
10-20+ years
Peaceful, active
4-24°C (coldwater species)
Omnivore (flakes, pellets, vegetables, live foods)
6.5-8.0
£1-£5 per fish
How Many Common Goldfish Should You Keep?
Common goldfish are social and do best with companions.
- Keep at least 2 goldfish where possible
- Stocking should match tank or pond size
- Allow plenty of space due to their size and waste production
Overstocking can lead to:
- Poor water quality
- Stunted growth
- Increased disease risk
For long-term care, ponds are often the best option.
Ideal Tank or Pond Conditions for Common Goldfish
Providing the right environment is essential for their health and growth.
- Tank Setup: Large aquariums with strong filtration and open swimming space
- Pond Setup: Outdoor ponds are ideal for adult goldfish
- Substrate: Sand or smooth gravel works well
- Plants & Decor: Hardy plants and open areas for swimming
- Water Conditions: Stable, well-oxygenated water
- Filtration: Strong filtration is essential due to high waste output
- Lighting: Natural or moderate artificial lighting
Regular maintenance is key to keeping water clean.
Compatibility with Other Fish
Common goldfish are peaceful but have specific compatibility requirements.
- Good Tankmates: other common goldfish, comet goldfish, and similar coldwater species
- Avoid: tropical fish (different temperature needs), very small fish, and slow fancy goldfish (may be outcompeted)
They are fast swimmers and may outcompete slower fish for food.
Are Common Goldfish Easy to Care For?
Common goldfish are often considered easy, but they require more space and maintenance than many people expect.
They require:
- Large tanks or ponds
- Strong filtration
- Regular water changes
- A balanced diet
They are hardy, but poor care (especially small tanks) often leads to health problems.
Common Goldfish Price in the UK
In the UK, common goldfish typically cost between £1-£5 per fish.
Prices vary depending on:
- Size and age
- Colour variety
- Shop vs hobbyist sellers
They are widely available and very affordable.
Where to Buy Common Goldfish in the UK
Common goldfish are widely available in UK aquarium shops, garden centres, and from private sellers.
Sourcing fish locally can:
- Reduce transport stress
- Improve survival rates
- Offer better value
TankMate UK helps connect fishkeepers and pond keepers who want to buy, sell, or rehome fish safely - without shipping.
Can You Sell Common Goldfish?
Yes - common goldfish are frequently rehomed, especially when they outgrow tanks.
Selling locally is often the best option, as it:
- Minimises stress for the fish
- Avoids the risks of transport
- Helps find suitable long-term homes
TankMate UK allows you to list fish quickly and find local buyers.
Feeding Common Goldfish
Common goldfish are omnivorous and should be fed a varied diet.
Key Tips:
- Feed high-quality goldfish pellets or flakes
- Supplement with vegetables (peas, spinach, lettuce)
- Offer occasional live or frozen foods
- Avoid overfeeding to maintain water quality
Common Problems with Common Goldfish
Stunted growth, often caused by:
- Tanks that are too small
- Poor water quality
Poor water quality, due to:
- Overfeeding
- Inadequate filtration
Swim bladder issues, linked to:
- Poor diet
- Overfeeding
Why Common Goldfish Are So Popular
- Extremely hardy and adaptable
- Affordable and widely available
- Active and engaging behaviour
- Suitable for ponds and large tanks
- Long lifespan
When kept correctly, common goldfish can thrive for many years and grow into impressive, active fish.
Frequently Asked Questions
They typically grow to 20-30 cm, but can grow larger in ponds.
No, bowls are unsuitable due to lack of space and filtration.
No, they are coldwater fish.
At least 120 litres for one fish, with larger setups or ponds preferred.
Looking to Buy or Sell Common Goldfish Locally?
TankMate UK connects fishkeepers and pond keepers who want to buy, sell, or rehome fish safely within their local area.
Whether you're stocking your tank or pond or passing fish on to a new home, you can:
- Browse fish available near you
- List your own fish in minutes
- Avoid the risks of transport