How-To Guide
Choosing the Right Aquarium Size
Choose an aquarium size from the adult size, group size and swimming habits of the fish you want, not from the space on a shelf. Larger tanks are more stable and offer more choice, but they weigh more, cost more to run and need a strong, level stand and floor.
Why Aquarium Size Matters
Aquarium volume affects stocking options, swimming space, water stability, equipment choices, maintenance workload, and the physical space required in the home.
Choose Size Around Adult Livestock Needs
Plan around adult body size, activity, social grouping, territory, waste production, and swimming behavior instead of buying a tank first and forcing species into it.
Water Volume and Stability
Larger water volume can dilute waste and slow some temperature or chemistry changes, but it does not replace cycling, filtration, testing, or maintenance.
Footprint, Shape, and Swimming Space
Two tanks with similar volume can function differently because length, width, height, and surface area influence swimming room, aquascaping, gas exchange, and territorial layout.
Stand, Floor, and Placement
Water, glass, substrate, rock, and equipment make aquariums heavy, so the stand must be level and designed to support the filled system safely.
Budget and Maintenance
Larger tanks can require more substrate, lighting, heating, filtration, water, and livestock, while very small tanks can demand especially careful stability management.
A Practical Way to Choose Your First Size
Choose the largest appropriately shaped aquarium that comfortably fits the intended livestock, safe location, realistic budget, and maintenance routine rather than simply maximizing gallons.
Frequently Asked Questions
What Size Aquarium Is Best for a Beginner?
Roughly 60 to 100 litres. It is stable enough to forgive mistakes but still manageable to maintain and move.
Are Small Tanks Easier to Look After?
No. Small tanks need less work per change, but temperature and water quality shift quickly, so mistakes show sooner.
Does Tank Shape Matter as Much as Volume?
Yes. A long tank gives more swimming room and surface area than a tall tank of the same volume.
How Heavy Is a Filled Aquarium?
Roughly 1 kg per litre of water, plus glass, substrate and rock. A 100 litre tank can weigh well over 120 kg.