try this....
15 tetras to form a large school.
a pair of rams or aspito's search them up on google. they're a type of dwarf cichlid that are very peaceful and look beautiful.
and one bristle nose pleco or 3 or 4 oto's for algae and you will be perfectly stocked.
this is my dream tank but right now i have a 12 gallon so there isnt much i could do.