I take it its the Juwel 180Litre?
Think fish says you can have:
Stocking Level in cms: 216
Stocking Level in inches: 85.04
So... are you after more dither/midswimming fish?
Depending on setup, you could add a couple more bristlenose, and see if they breed?
You could add danios, lemon tetras, glowlights or a pair of gouramis for instance?
Personally, I might perhaps add some penguin fish or black tetras...