Usually nano fish are around or just under an inch and probably no more than 1.5-2" or so...very subjective but tends to be fish people keep in tanks that are 10g or less because of their size. However because of your dimensions they are a good fit because they don't need as much space lengthwise as those you normally see fit for a 20g water volume.
Microrasboras, smaller tetras and danios, small cory species, small anabantoids or killifish...quite a bit out there now for smaller tanks.
Microrasboras, smaller tetras and danios, small cory species, small anabantoids or killifish...quite a bit out there now for smaller tanks.
