Purple dottyback aggression please help

[Mreardon93]

I have had this pair of pajama cardinal fish since 2017 and they have done very well in my 65 gallon tank and have grown pretty large. I also have a pair of clowns and a tomini tang. Most recently I added a purple dottyback to the tank and everything was fine for a little over a year. I figured that this was because all of my fish were well established and in adding the dottyback last that the aggressiveness was curbed. This month however I’ve been away for school and my sister has been taking care of the tank. Long story short there was some neglect in cleaning the tank properly and one of my cardinal fish sadly died, which surprised me considering how much they have been through since 2017. Well for whatever reason, the dottyback which has paid no attention to the cardinal fish for over a year decided that now was his opportunity to strike since there was only one cardinal fish for him to take on. When I came home to visit I found that my cardinal fish was being chased around the tank pretty frequently by the dottyback although there was little to no fin nipping or anything to that degree. Regardless, I did not want to take any risks of the aggressiveness escalating so I purchased 3 more pajama cardinal fish in hopes to spread out the aggression and prevent any issues. So far I have been happy with the cardinal fish as they all seem to school and my larger cardinal fish seems to be less stressed than before. However, the dottyback still seems to only chase the large cardinal fish and I am unsure as to why he pays no attention to the smaller new ones. I am hoping that over time the dottyback will take his focus off my larger cardinal fish but I was hoping for any input on why this is happening or anything I could try to see if I can get him to spread out his aggression instead of targeting just one fish. Thanks for the help!

 

[BaliReefBox]

I also have one of the dottyback and for 3 months all has been good. I changed tank to a larger one now the dotty has gone all macho and is chasing everyhting, especially at feeding times.. be interesting to see what the experts say.