Ideas For Unusual Fish?

[Crock17]

I'm fairly new to the forum, and to fish keeping. I currently have a Juwel Rio 180 but am already looking to upgrade, it's been set up a few months now and is stocked with:

1x standard plec
3x tiger barbs
3x tin foil barbs
3x cherry barbs
4x silver sharks
1x red tail black shark
2x cory sterbai
2x red tail blue botias

Can anyone suggest some more unusual fish to add that would be ok with what I already have? As I said I will be upgrading hopefully fairly soon but my current fish are fairly small (except for 25cm pleco) do over stocking isn't a problem short term?
1x feather fin synodontis

 

[micko]

Any experience of botia's I've had hasn't been good. They're quite unfriendly.
Silver sharks grow up to 14 inches and need to be in groups of at least 6. So a massive tank would be needed for them alone.
Tiger barbs and cherry barbs will need a larger number too. The larger the better as they can be quite nippy to others. At least 10 of each.
Increase the corys to a minimum of 6.
I'm not a 100% sure but I think tin foils grow large.
The plec, if its a common plec will grow up to 24 inches.

I wouldn't add anymore fish, I'd sort out the stocking in your tank first.