I go for Killifish...No suprise there.
Nothobranchius rachovi is probably a good example of a colourful fish.
http/1.bp.blogspot.com/_zJwlAOWttdA/SgwIeHSaaiI/AAAAAAAAAt8/JEq3YCb9Bx4/s400/nothobranchius_rachovii_.jpg
Regards
C
large or small?
I would say for community tank things like colombian tetra's/neon tetra/cardinal tetra/ticto barb/cichids from lake malawi for a species tank,jewel cichlids to name but a few
I think the malawi cichlids like the kenyi and socolofi, when you have the right lighting you can get the best colour out of them like in mine I have a blue and white light tubes, it makes my scolofi look like marine fish