So I have had my 55 gallon tank established for about 7 months now. And all I've had in the tank for the last 5 months are two angels who are now rather large. And until recentl, have had no problems whatsoever with aggression. I will add, that for the last 3 months I didn't change the water once, or test it. I had got super busy and all I did was feed them. Well the past week I tested the water , realized it was in pretty bad shape and did 2 50% water changes and added 2 Bolivian Ram cichlids today who have also been real aggressive to each other. I know both species tend to not be very aggressive, there is plenty of cover in there for the rams and what should be enough cover for the angels, as it has been for the last 6 months. Is it possible that it is because I changed the water twice this past week ? No matter the cause , how can I stop the aggression from the one angel, and the two Rams. I have two more blue rams coming in tomorrow.And I'm just not sure why all this aggression came out of nowhere. Or could it be my tank layout?