Too start I would paint the back of the tank Black, then fill the bottom of the tank with 5" sand & gravel mixture, add water, plants and a few Lg. rocks/Broken Clay Pots and a nice center piece of driftwood. Then finish everything off with the addition of 350 sm. neon, 150 sm. Black tetras and 4 small cats and call it. Feed them once per day a pinch or too of food, once per month water changes, what could be easier.
OR..... Depending on the budget.
If I was in that sort of mood or I decided to place this tank in another area of the house I mite go with a larger fish. Still a good gravel bed of 3 inches medium size pebbles, paint the back glass Black, a few Lg. pieces of diftwood and a couple of broken clay pot pieces, all topped off with 17 varying sizes of Red Parrot Fish, and 1 Lg. Pleco and a Medium Catfish or too. A few more water changes per month and yes more feedings and food.