A 5 gallon can fit on a desk. Or a sideboard or table or something. If you have or can create such a space near a power supply ( and I would find it
very hard to believe most people cannot manage this in some way ) then there should be no problem. 5 gallons will be far easier to keep stable in terms of water parameters, you can
easily find filters and heater to fit them properly as opposed to smaller tanks, and the fish has more space to swim.
Seriously. A 5 gallon tank, 25 or 50 watt heater set to 27 degrees minimum, and a simple sponge filter are the bare basics. Some soft silk or live plants, sand or gravel, perhaps a smooth piece of wood or a smooth nice ornament to give the fish interest, and a more natural environment as well as resting spots, and you have a great little setup that is easily managed.
A 12 inch square cube would give you roughly 5-6 gallons which is just fine for a nice male and perhaps a few shrimp as company .
My tank is a 5 gallon hexagonal tank, which would take up less deskspace than a cube or rectangluar tank if you can get one similar. Look:
That tank is on a small table in the corner of the dining room.
