[fishstein]

I'm about to set up my first sub 75 gallon aquarium (though I've had +30 gallon palludariums) and was wondering what would you consider the upper range of a nano tank?

I'm planning on setting up a 20 gallon this week, which while it may not be thought of as nano, I plan to aquascape with rocks and small enough plants to make a very large looking scene in a small space (a core aim of zen gardening).

 

[fishfan]

Interesting question I'd like to know too. Even a 15-20 gallon tank can become quite small once plants are growing strong.

 

[ALIFER]

I think in reef tanks the term Nano has been expanded to pretty much include 30 gallons & below.
And the term Pico has been used for below 5 gallon tanks.

-Rick

 

[Squawkbert]

For FW planted - I generally think of:
Micro <10g
Nano <5g
Pico <2g
Femto <1g
Atto = Betta cup