I wanted to add just one yellow tail damsel. To my 30g with pair oc clowns and a firefish already in there. My LFS said better to add 3 to 5 of them to prevent aggression. My LFS is pretty good but this sounds odd to me I would think more of them would cause more aggression. I like to keep bio load low. The most I would add would be 2. Or just don't add any. anybody have any thoughts? thx