5 Gallon

Also sold as 5.5 Gallon

5 Gallon is a 40.6 × 20.3 × 25.4 cm (16 × 8 × 10 in) aquarium, rated at 21 L (5.5 gal). Its footprint is 40.6 × 20.3 cm and the water stands about 19.4 cm deep once a 6 cm substrate layer is in — the two numbers that decide what you can plant in it and what you can stock it with.

Start a tank this size

At a glance

Size40.6 × 20.3 × 25.4 cm (16 × 8 × 10 in)
Volume21 L (5.5 gal), as sold
Water after substrateAbout 15 L (4 gal) with a 6 cm substrate layer
Footprint40.6 × 20.3 cm (16 × 8 in)
Water depth19.4 cm (7.6 in)
Substrate neededAbout 5 L for a 6 cm layer

Before it goes in

  • 5 Gallon is 40.6 × 20.3 × 25.4 cm (16 × 8 × 10 in) — rated at 21 L (5.5 gal), and roughly 15 L (4 gal) of actual water once a 6 cm substrate layer and the hardscape are in.
  • That layer takes about 5 L of substrate, which is what you order by.
  • 15 of the 160 animals in this library list a minimum tank at or under 21 L (5.5 gal). The biggest of them that still fit are Amano Shrimp and Crystal Red Shrimp. Ember Tetra and Chili Rasbora need more than this.
  • The water sits about 19.4 cm (7.6 in) deep over the substrate. Plants that get taller than that — Hygrophila corymbosa 'Siamensis' and Water Sprite — reach the surface and start growing along it, which is a look you either want or trim.
  • Its footprint is 40.6 × 20.3 cm, and that is the area a carpet has to cover — the number that decides how many pots you buy, not the volume.

What are its dimensions?

40.6 × 20.3 × 25.4 cm (16 × 8 × 10 in).

How much water does it hold?

It is sold as 21 L (5.5 gal), and roughly 15 L (4 gal) of actual water once the substrate is in. Stocking works off the second number; minimum-tank-size advice works off the first.

How much substrate does it take?

About 5 L for a 6 cm layer.

What fits in it?

15 of the 160 animals in this library list a minimum tank at or under its volume, and the water depth of about 19.4 cm sets which plants can grow without reaching the surface.

What fits in it

Often compared with

5 Gallon36PFluval Spec V
Size40.6 × 20.3 × 25.4 cm36 × 22 × 26 cm52 × 19 × 29 cm
Volume21 L21 L19 L
Footprint40.6 × 20.3 cm36 × 22 cm52 × 19 cm
Water depth19.4 cm20 cm23 cm

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