The Most Popular Fish for Aquariums in the UK: A Guide for Beginners and Enthusiasts

Keeping an aquarium is one of the most rewarding hobbies, bringing a sense of calm and a slice of underwater life into your home. Whether you’re a complete beginner or an experienced aquarist, choosing the right fish is essential for maintaining a healthy and thriving tank.

In this guide, we’ll explore some of the most popular fish species kept in UK aquariums, highlight the best options for beginners, and outline which species are better suited to experienced keepers with specialised setups.

Why Choosing the Right Fish Matters

Before diving into specific species, it’s important to understand that not all fish are equally easy to care for. Factors such as tank size, water parameters, compatibility, and feeding requirements all play a crucial role.

Choosing the wrong fish can lead to:

• Poor water quality 
• Aggression between species 
• Shortened lifespans 
• Increased maintenance 

Starting with hardy, low-maintenance species is always the best approach for beginners.

Best Fish for Beginners

If you’re new to fishkeeping, these species are widely available in the UK, relatively easy to care for, and forgiving of minor mistakes.

1. Goldfish

Goldfish are one of the most recognisable aquarium fish and a traditional favourite in UK households.

Key features:

• Hardy and adaptable 
• Long lifespan (often 10+ years) 
• Suitable for beginners 

Things to consider:
Goldfish grow much larger than many people expect and require spacious tanks with powerful filtration. Contrary to popular belief, they are not suited to small bowls.

2. Guppies

Guppies are small, colourful fish that are perfect for community tanks.

Key features:

• Very easy to care for 
• Peaceful and sociable 
• Wide variety of colours and patterns 

Things to consider:
They breed rapidly, so be prepared for population growth if males and females are kept together.

3. Neon Tetras

These striking little fish are known for their bright blue and red stripes.

Key features:

• Ideal for smaller tanks 
• Peaceful and best kept in groups 
• Add vibrant colour to planted aquariums 

Things to consider:
They prefer stable water conditions, so a properly cycled tank is important.

4. Betta Fish (Siamese Fighting Fish)

Bettas are known for their flowing fins and bold personalities.

Key features:

• Can be kept alone in smaller tanks 
• Hardy and adaptable 
• Visually striking 

Things to consider:
Male bettas are territorial and should not be housed together.

5. Platies

Platies are lively, colourful fish that are ideal for beginners.

Key features:

• Peaceful and community-friendly 
• Easy to feed and care for 
• Active and engaging to watch 

Things to consider:
Like guppies, they are livebearers and can reproduce quickly.

Popular Fish for More Experienced Aquarists

As your confidence grows, you may wish to explore more advanced species that require specific conditions or care.

1. Angelfish

Elegant and graceful, angelfish are a favourite in larger aquariums.

Considerations:

• Require taller tanks 
• Can become territorial 
• May eat very small fish 

2. Discus Fish

Often considered the “king of the aquarium”, discus fish are stunning but demanding.

Considerations:

• Require precise water conditions 
• Need warm, clean water 
• Sensitive to stress 

3. Cichlids (Various Species)

Cichlids are intelligent and colourful but can be aggressive.

Considerations:

• Species-specific compatibility 
• Often require specialised tank setups 
• Can be territorial 

Fish Beginners Should Avoid

Some fish are commonly sold but are not suitable for beginners due to their size, care requirements, or behaviour.

1. Common Pleco

Often marketed as algae eaters, plecos grow far larger than most expect.

Why to avoid:

• Can grow over 45 cm 
• Produce significant waste 
• Require very large tanks 

2. Marine (Saltwater) Fish

Saltwater aquariums are beautiful but complex.

Why to avoid:

• Expensive setup and maintenance 
• Sensitive species 
• Require specialist knowledge 

3. Arowana

Arowanas are impressive but completely unsuitable for most home aquariums.

Why to avoid:

• Grow extremely large 
• Require huge tanks 
• Need specialised care 

Tips for First-Time Aquarium Buyers

If you’re setting up your first aquarium, taking the time to get things right from the beginning will save you a lot of frustration later on. It is also well worth taking speaking to experts such as those at Complete Aquatics to get advice and help avoid costly mistakes.

One of the most common mistakes is rushing the process. Aquariums need time to establish a healthy biological balance, so it’s important to cycle your tank properly before adding fish.

Tank size is another key consideration. While smaller tanks might seem easier to manage, they are actually less stable and more prone to sudden changes in water quality. Starting with a slightly larger tank often makes things easier for beginners.

It’s also worth investing in good-quality equipment from the outset. A reliable filter, heater (for tropical fish), and water testing kit will help you maintain consistent conditions, which is essential for fish health. Skimping on these basics can lead to ongoing problems.

When it comes to stocking your aquarium, less is more. Overcrowding is a common issue that can quickly lead to poor water quality and stressed fish. Introduce fish gradually and ensure they are compatible with one another.

Finally, patience is key. Regular maintenance, including partial water changes and monitoring water parameters, will keep your aquarium in good condition. Building a successful tank takes time, but the results are well worth the effort.

Final Thoughts

Starting an aquarium can be an incredibly rewarding experience, but success comes down to careful planning and responsible fish selection.

For beginners in the UK, species like guppies, platies, and neon tetras provide a colourful and manageable introduction to fishkeeping. As your experience grows, you can gradually explore more complex species such as angelfish or discus.

Above all, research each species thoroughly, invest in proper equipment, and remember: a healthy aquarium is built on patience and consistency.