Really does depend on the fishes temperament. In this house we have 2 siamese fighters (not in the same tank), one is very sociable living happily with ember tetras, neon tetras, pearl danios and a bristle nosed plec (admittedly he did eat one very small ember when I first introduced them but I think this one was not doing well so feel nature maybe did its thing) BUT the other fighter will not accept any other fish apart from a bristle nosed plec, these fighters are completely different so it is very hard to advise you.