Basic question

BTW, you could do a very nice little planted nano set-up with your one gallon if you want. Check out the plantedtank forum, 'Planted Nano Tanks' for more info on how to go about it.

If you use florite substrate you could put in several real plants like java moss, HC, dwarf hairgrass and maybe Anubias Nana petite that would sustain some cherry shrimp. Cherry shrimp can be as interesting to watch as fish IMO. With a good light and regular small water changes you could probably use the plants as a natural filter for the shrimp. Just an idea.
 
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