Aquarium Tanks for Sale: A Practical Buying Guide

Choosing the right aquarium tank is the single most important decision you'll make as a fishkeeper, because it determines which fish you can keep, how stable the water conditions will be, and how much ongoing maintenance you'll face. Bigger tanks are generally more forgiving for beginners, as larger water volumes dilute waste and temperature swings, making the tank more stable than a small bowl or nano tank. Before buying, think about where the tank will sit (a full tank is extremely heavy, so floor loading and a proper stand matter), whether you want a tropical setup with a heater or a coldwater tank without one, and how much filtration capacity you'll need for your intended fish stocking. Glass tanks are scratch-resistant and budget-friendly, while acrylic is lighter and clearer but scratches more easily. Also consider the tank's footprint rather than just its volume - a long, low tank often provides better swimming space and gas exchange than a tall, narrow one. This guide covers the key things to check before you buy, plus common questions new and experienced fishkeepers ask.

Key Things to Consider Before You Buy

Size and stocking. Work out roughly what fish you'd like to keep first, then choose a tank that comfortably suits their adult size and social needs, not just what fits your budget today. It's far easier to under-stock a large tank than to cram fish into one that's too small.

Material. Glass and acrylic both have their place - glass is the standard choice for most home aquariums thanks to its durability and value, while acrylic suits unusual shapes or situations where weight is a concern.

Location and support. A stocked aquarium is heavy, so always place it on a stand or cabinet designed to hold its full weight, on a level floor, away from direct sunlight (which encourages algae) and draughts.

Equipment. A tank is only the start - you'll also need aquarium equipment essentials such as a filter, lighting, substrate and, for tropical setups, a heater. Don't forget the smaller tank accessories like nets, water conditioners and test kits that make day-to-day care easier.

Tropical vs coldwater. Decide early whether you're setting up a heated tropical aquarium or an unheated coldwater tank, as this affects your equipment list and which fish and plants are suitable. If tropical fishkeeping appeals, it's worth looking at dedicated tropical fish tank setups designed with the right equipment already in mind.

Live plants. Hardy aquarium plants such as Amazon sword, java fern and anubias are good choices for beginners, tolerating a range of lighting and water conditions while helping to keep water quality stable.

Ready to compare options? You can browse our full range of fish tanks and aquariums, and it's always worth checking our current clearance deals on tanks and equipment before you commit to a full setup.

Frequently Asked Questions

What size aquarium tank should I buy?

As a general rule, buy the largest tank your space and budget allow, since larger volumes of water are more stable and easier to maintain than small ones. For most tropical community fish, a tank of at least 60 litres (around 2 feet) is a sensible minimum, though many species need considerably more.

Is glass or acrylic better for an aquarium tank?

Glass tanks are heavier but more scratch-resistant and generally cheaper, making them the most common choice for home aquariums. Acrylic tanks are lighter and offer clearer viewing, but they scratch more easily during cleaning, so consider which trade-off suits your setup.

Do I need a filter and heater with every aquarium tank?

Almost all aquariums need a filter to process fish waste and keep water quality safe, regardless of species. A heater is only needed for tropical fish that require a stable warm temperature; coldwater fish kept at room temperature don't need one.

How long should I wait before adding fish to a new tank?

A new aquarium needs to go through the nitrogen cycle before it's safe for fish, which typically takes 4-6 weeks of running the filter and dosing an ammonia source. Adding fish too soon is one of the most common causes of early fish losses in new tanks.

Can I put a large aquarium tank on any floor or shelf?

No - water weighs roughly 1kg per litre, so a 100-litre tank plus substrate, decor and the tank itself can weigh well over 120kg. Always use a stand or unit rated for the tank's full weight, and check floor loading for larger tanks, especially upstairs.

What's the difference between a tropical and coldwater aquarium tank?

A tropical aquarium is heated to maintain a stable warm temperature suited to species like tetras and gouramis, while a coldwater aquarium is kept at ambient room temperature for species that don't require added heat. The tank itself can be identical - it's the equipment and fish stocking that differ.