Aquarium Tank Sizes Explained: 2ft to 6ft in Litres, Dimensions and Weight
By Melbourne Tropical Team ยท 2 min read
How big is a 3ft, 4ft or 5ft fish tank in litres, what does it weigh full, and which size is right for you? A clear, no-jargon guide for Australian fishkeepers.
Why tank size matters more than anything
The size of your tank is the single most important choice you will make. A bigger tank holds more water, and more water is more stable - the temperature, pH and waste levels swing far more slowly, which means healthier fish and fewer emergencies. This is why the old advice to 'start small' is backwards: a larger tank is actually easier for a beginner.
Common Australian tank sizes (approximate)
Tanks are usually sold by length in feet. These are typical volumes for standard shapes - always check the exact litres for your model, as height and width vary.
- 2ft (60cm) - around 60-75 litres. Good for a betta, a small community or shrimp.
- 3ft (90cm) - around 110-130 litres. A great first community tank.
- 4ft (120cm) - around 200-240 litres. Room for a proper community or medium cichlids.
- 5ft (150cm) - around 280-340 litres. Suits larger or messier fish.
- 6ft (180cm) - around 400-500+ litres. For big fish like oscars, large cichlids and community showpieces.
How much does a full tank weigh?
Water weighs about 1 kg per litre, and the glass, substrate and rocks add more. As a rule of thumb, a full tank weighs a little more than its volume in kilograms - so a 200-litre tank weighs over 200 kg once filled. That is far too heavy for most furniture, so always use a proper aquarium stand or cabinet rated for the weight, and sit it on a solid, level floor.
Use our aquarium volume calculator to work out the exact litres from your tank's measurements.
Which size should you choose?
Buy the biggest tank your space, budget and floor can safely handle. For a first tropical community, a 3ft (110L) or 4ft (200L) tank hits the sweet spot of stability, choice of fish and manageable cost. Avoid tanks under about 40 litres unless you are keeping a single betta or a shrimp tank.