I know the feeling of trying to grow plants without proper lighting- a struggling plant is worse than none- they make a mess.
Do you have a cover? if not, try planting bog plants, non-aquatics - "lucky" bamboo, or pothos or peace lilly- they will all root in water
If you're not intersted in live plants there is plenty of decor you can use- fancy marbles (uggh) or even a plain river rock type scape.
You can probably grow Java moss, that stuff grows in the dark- cut a piece of dead azalea branch and use it to make the base and branches of a tree- when the moss grows in it will look great.
You can even go off the wall- I used to have a small tank that had a skull from some animal I found in the woods. It was very cool- and a bleached skull would look intense on a black sand substrate.
If you're a creepy kinda person who likes to freak out their friends, get an old baby doll, pull the head off, hot glue some rocks inside so it sinks and take one of its eyes out- I saw one of these after it grew some algae on it and it FREAKED ME THE F$&% OUT-
So what would you like to do? Your options are endless
