Hello all please excuse me I kinda new at thsi....... I have a 55 gal tank, in it I had 3 Zebra Danios, 4 Glow Lite Tetra, 4 Cardinal Tetra. Yesterday I added 4 Blood Fin's, once they got into tank 1/2 hr 45 min later they started bossing the Cardinals around and all of a sudden today one of them is MIA. They seem to leave the Danios alone for the most part but they are trying to be king of the roost. Stuff I read on them says they are not really aggressive and get along. Do I need to fear for my other fish or in a few days will they all work out their domain and that be the end of it?! I had a couple bala's for awhile and when they went in they didn't bother the smaller fish.