I have a 30 gallon, 31 inch long tank with 3 yellow tailed damsels and 1 black neon damsel. I have created a ridge with plenty of places to hide and all 4 of the damsels are settled and tolerant of each other. They were the first in the tank and no other species of fish have been housed with them. My wife would like to purchase 2 clown fish. Would this cause any problems?