Inspirational aquariums: Iwagumi with Rummynoses


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We spotted this lovely display at a trade show. It's been created in the aquascaping style called iwagumi.

The design works because it combines just four elements — one species of plant, one type of rock, uniform black gravel and one species of fish, the Rummynose tetra.

The term iwagumi basically means rock garden and Japanese enthusiasts originally created mini-mountain scapes first in their gardens, then later as projects in their aquaria.

The iwagumi has become a very popular style of aquascape and its characteristic areas of open water and shoals of small fish present very calming scenes.


The right rocks and the way they are arranged, is crucial to the iwagumi design.

The rock of choice for this style of aquascape is usually limestone, as weathering causes the characteristic aged looking striations and lines on the surface.

Choose the right shapes and arrange them the right way, and a small 20cm/8” diameter rock can resemble a mountain!

Look out for Mini Landscape rock, ADA Seiryu stone or similar, and arrange these according to Zen rock arrangement design rules.

You will need around 40 kilos/88lb of your choice of rock for a tank this size.


To keep the design simple, imitate what’s here. The plant species is new and called Pogostemon helferi, or Downoi.

It’s quite easy to keep and only needs moderate lighting and fertilisation, although CO2 injection is always recommended for any planted tank.

Remove from pots, separate and plant only in and around the rocks, leaving the foreground plant free. You’ll need upwards of 12 pots to get this look.


Only Rummynose tetras (Hemigrammus bleheri) have been used, although you could also get very good results from just having Cardinal tetras (Paracheirodon axelrodi).

A lot of fish have been used here, although you must pre-mature the filter with other fish if adding lots at once. Best build up the shoal size gradually, using a test kit to monitor water quality as you go.

You’ll need upwards of 30 Rummynoses to achieve this look.

At a glance

Tank size: 120cm/4’ long, 240 l/53 gal volume.

Start-up costs: About £1,000, including lighting and CO2.

Ease of project: Moderate.

Time needed: One day to complete the aquascape, one month to mature.

Check out some of our other inspirational aquariums:

Discus the centrepiece

Modernist approach

Low maintenance island tank

Planted pico

Zebra plec breeding set-up

Calming moss tank

Rocky cichlid tank

Fun iwagumi

Classic nature aquarium

Medium sized reef tank

Posh nature aquarium

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