I currently keep a small sailfin tang and a small niger trigger together and I havent had any problems as far as aggression..The sailfin was added first then the niger.. they are in a 125g with a coral beauty, a potters angel, a christmas wrasse, and 2 purple damsels...........
175g RR FOWLR
(just started adding a few corals)
55g Mixed Cichlids
20g long Turtle tank (2 red eared sliders)
20g fountain (2 shubunkins)
10g Fancy Guppy
starting a 29g mixed cichlid tank