A cube-shaped aquarium doesn't quite work like a long rectangular aquarium.
In a long tank, you often build movement from left to right. You can leave an open side, create a diagonal through the whole aquarium or place the main shape according to the rule of thirds.
In a cube aquarium, things are different. Because width, depth and height are closer together, the aquarium feels more like a small room than a long stage. Therefore, a central scape is often much stronger in a cube.
A central root, a central island or a compact group of roots, stones and plants can be just right, especially if there is open space around it.
Why the centre often works in cube aquariums
Many aquascaping guides tell you not to put everything in the centre. That advice is often good in rectangular aquariums, but it should not be used blindly.
In a cube-shaped aquarium, the centre may be the natural place.
A central scape allows the aquarium to be viewed from several angles. Fish and shrimp can move around the structure. Plants can be built up like an island. The root can gain height without the whole layout tipping to one side.
The important thing is that the centre feels chosen, not random.
A central root in a cube aquarium should ideally not just be a pole in the centre of the tank. It should have direction, level differences, openings and an uneven shape. This makes it central without feeling rigid.
You can read more about the basic principles in the article the golden rule in aquascaping.
Common dimensions of cube-shaped aquariums
Cube aquariums come in many sizes, but some measurements are often repeated. The volume below is the approximate gross volume before sand, roots, rocks and technology.
- 20 x 20 x 20 cm: approximately 8 litres
- 25 x 25 x 25 cm: approximately 16 litres
- 30 x 30 x 30 cm: approximately 27 litres
- 35 x 35 x 35 cm: approximately 43 litres
- 40 x 40 x 40 cm: approximately 64 litres
- 45 x 45 x 45 cm: approximately 91 litres
- 50 x 50 x 50 cm: approximately 125 litres
- 60 x 60 x 60 cm: approximately 216 litres
The real volume of water will always be lower when you put in substrate, root, stone and plants. In small cubes, every centimetre matters.
Choose root by depth of cube, not just width
In a rectangular aquarium, you often think of the front width first. In a cube aquarium, you need to think more three-dimensionally.
A root can be just the right width but still feel too deep. It can also be just the right length but too high. Because the cube has more depth from front to back, you often want a root that can be placed in the centre and built around, rather than a root that just lies along the back window.
As simple direction:
- in a 30 cm cube, small roots or a compact low root often work best
- in a 40 cm cube, a clearer central root can start to work really well
- in a 45-50 cm cube, there is often room for a root with more height or branching
- in a 60 cm cube, you can build a more advanced central island, forest feel or root group
These are just starting points. The shape is more important than the number.
A Tuskwood root that is low, curved or branched may fit perfectly in a cube even if it is not very large. Another root of the same length may feel too bulky if it blocks too much of the front or becomes difficult to plant around.
Build an island, not a wall
The most common mistake in cube aquariums is to build a wall along the back window.
It works sometimes, but then you lose much of what makes the cube special. The strength of the cube is its depth. You can see into the scape, around the roots and between the plants.
A central island often works better:
- a root or root group in the centre
- stone or substrate that builds up height around the root
- lower plants at the front and around the edges
- taller plants closer to the centre or back of the island
- free area around the structure
This makes the aquarium feel more like a small landscape than a background with decoration in front.
Leave free space around the scape
In a cube, the void is particularly important.
If the entire bottom is filled with material, the spatial feeling is lost. The aquarium will quickly become compact, especially in small sizes.
Try to leave a visible surface around the central scape. This could be sand, a low mat of vegetation, open soil or just a quieter zone where fish and shrimp can move around.
The free surface makes the root feel more deliberately placed. It also makes the aquarium easier to read.
Height is valuable, but should be used carefully
Cube aquariums often have more height than you first realise.
This can be a great advantage. A root that rises upwards, or plants that are allowed to build height around the centre, can give a very strong feeling.
But height can also make the scape heavy if everything ends up in a compact lump. Try to create openings. Let branches, plants and stones provide different levels. A root that leans slightly, or has a clear direction, often feels more natural than a root that just stands straight up.
Tuskwood works well here because the roots come in many different shapes: low, high, stout, narrow, simple and highly branched. In a cube aquarium, that variety is especially valuable, as the right shape can make the whole scape easier to build.
Smaller cubes require simpler expressions
In a 20 or 30 cm cube, there is not much space to waste.
A clear idea is often better than a lot of detail. A small central root, a few stones and a simple planting plan can go a long way.
Try to avoid mixing too many different root shapes, rock types and plants in a very small tank. It easily gets messy. A strong small scape is often more impressive than a small scape that tries to be too much.
In small cubes, WYSIWYG is particularly important. A few centimetres of error can change the whole layout.
Larger cubes can carry more drama
In a 45, 50 or 60 cm cube, there is more space to build a real central environment.
There, a stronger Tuskwood root can serve as a base. You can add smaller roots for support, build height with stone and create different levels for plants.
A larger cube can also support a more expressive root without everything feeling cramped. But here too, free space is important. It is often the contrast between the central scape and the surface around it that makes the tub beautiful.
In short
Decorating a cube-shaped aquarium is about using the shape of the cube instead of fighting against it.
In a long aquarium, the rule of thirds and laterally offset scapes are often strong. In a cube aquarium, a central island or central root is often the best choice.
Choose a root that works in three dimensions: width, depth and height. Build around it like an island. Leave free space around the scape. Use height, but create openings and direction.
With the right root, a cube aquarium can have a very strong feel, even when it is small. It doesn't just become an aquarium with a root in the centre. It becomes a small landscape that you can look into.