We had one Giant Danio die on us a while back, so I purchased a new companion for the giant Danio this was a couple of weeks back, the newer Gaint Danio is smaller and everytime he goes near the bigger one he chases him off
Hey I had this happen with some zebras.They eventually got used to each other and are now the best of friends.I think it just takes some time for them to establish a relationship.Althouh I have heard that if things dont calm down within 48 hours that there is less of a chance that they will ever except each other.And you might want to try a different danio.But for now just give them some time to adjust