The video shows the poor female Taiwan Reef cichlid with nibbled tail and the new (smaller and less colourful) female swimming nearby. She has been followed by a male and a bit harassed by the dolphin but I hope she will make a difference…
The new three have only been added this afternoon so I hope they all get along. Even though they are cichlids and a bit moody. Or a lot moody.
Please excuse the footy commentary, etc in the background. Not very professional I know…
aquariumsetup 
Try netting the aggressive guy for about 15 seconds and put back in. Or rearrange rockery in tank…keeps aggression down