Ooh, ooh, ooh! My 20 is just... plants and caves. Lol. It's divided for three.
My ten is split in half. Harmonia's side has pink accents in the gravel, a girly lily type silk plant that spans pretty much the whole back of her half of the tank, and a unicorn figurine and a bunch of grass like plants.
Erasmos's half has kind of a... marshy like feel to it. The brown gravel with a root type thing in there and a bunch of leafy and grassy plants.
Banana Fish is a king in his 2.5, with a castle with blue accents to highlight his blue coloring on his caudal fin, and several stately looking plants in with him. <3 He's probably my secret favorite. :o