New to saltwater aquarium hobby I have 4 fish on my nano aquarium is 20 gallon I have one O. clownfish(she’s the boss), green chromis, royal gramma and bicolor blenny, I wanna add 2 more fish. Is possible to add a bengal cardinal and peaceful damsel or should I get other type of peaceful fish instead of a damsel knowing that most damsels are aggressive and territorial but I heard that sapphires damsel and Talbots are more in the peaceful side.