What goes in the empty space in my photo?

I would suggest a taller item, i.e. obelisk, or a small tree-shaped item. This would cause your corner to be noticed and bring the eye up. Good luck!!

a succulent plant would be great.

Typically, Asian decor is kept very simple and zen-like. Is it possible to shift the center pieces to the right, moving your fern to the center of the shade? If you don't care for that look, might you try removing the vases and urn to another spot in the bathroom because the center pieces are a similar height? A tall candle might be pleasing in the middle if you do move the vases and urn. The pieces you have are nice. I think I even have the same tall vase and perhaps? matching urn . You just have to experiment until the area pleases YOU. With the space a garden tub provides, I think you are headed in the right direction.

Buy a Luminara candle they look real they use them in or outdoors and are beautiful for the space . I would put ithe candle in Asian glass lantern . It will not set off the alarm.

An Oriental Figurine

Just noticed your included comment about candle setting off alarm....it can be just for looks OR one of the better candles that flicker with out a flame!

A big Buddha would look great.

I guessing from the photo it's the ledge of a spa tub?? Candle sticks with battery operated candles will do the job. I'm a huge fan of Asian themed decorating. Love it!!

I wouldn't add anything else. I would re-position what's there to eliminate the space. I would put three tall wooden paint brushes in the vase in the corner to add height.

I know the kind of brush you mean. I'll be on the lookout. I would never have thought of that. My son just might have some in his old art supplies. Thanks. 😇

Hello, to a former neighbor. I also had an afterthought, you might use a tall pedestal and a red candle. That would be lovely!

ONe of my favorite things about asian decor is the minimalism...less is more,do Not think of the space as empty but as breathing space\\\

Looks like you have ENOUGH STUFF, AS IS.. White or blank space allows eye to appreciate each item. Consider designing other vignettes and rotating them seasonally.

You don't need anything else. Gently space everything a bit more apart. If you add anything else it will look cluttered and chintzy.

I think you need something tall and slinder behind the 3 vases in the very corner with some green folage or sprigs of golden wheat. You could always spray paint a tall bottle or vase gold and let the folage spill over the edge to the table top a bit . make sure the height of the finished corner is a little taller than the round art piece! Looks nice what you already have! good luck

Another plant.