New Tank mates?

[synoguy]

i have a 150 gallon tank with:
1x blue acara
1x Green severum
1x synodontis euperteus
1x rainbow fish (rehomed from a neighbour)
1x YOYO loach (also rehomed)
2x bristle nose catfish
1x Angel fish

i would like something colourful and attractive but not something i akready have.
thanks for any advice given. pictures will be greatly appreciated
Alex