Possible Tank Mates?

[alex454243]

I currently have in my 180 litre tank:

1 x Red Tail Shark
1 x Golden Sucking Loach
1 x Dwarf Suckermouth Catfish
2 x Edlers
2 x Odessa Barbs
2 x Shrimp
3 x Pentazona Barbs
4 x Neon Tetras
4 x Black Tetras

I was wondering what people think I could and should add to my tank, I am never sure what would go well with the RTS as he can be rather aggressive towards medium/large fish, as can the odessa barbs!!

Cheers
Alex