Male kribs can be very aggressive like that. I would not advise any dither fish for kribs. From what we have discussed in the tropical forum, the kribs would attack, and most likely kill, the dither fish during breeding. I think that the gourami should be fine though, watch out for aggression witht eh krib, because male kribs really like to pick fights, and from Glenbo's experience, they don't always win...