what i did was buy a mini pumkin (no bigger then 3 inches across, 2 inches tall). I then hollowed it out, & carved it. Then i cut up a candle small enough to fit in the space i provided, and cut a hole in the top of the pumpkin where the stem is so it can burn without being put out :3
so i have a flickering REAL jack-o-lantern right next to the tank. I turn it on at around 6, and it's so cute until i turn it off at around 11 when i go to sleep. it glows CRAZY BRIGHT because theres so many holes and the walls of the pumpkin are so thin.
also, i have a pumpkin style candle next to that. Together, the candle-lit lights give the perfect halloween look to the tank :3