About 6 months ago I bought a Neon Dottyback who has been one of the more beautiful additions to my reef tank. I never knew how aggressive they were until I added a Watchman Goby and the Dottyback started bullying the Goby until he died. I was at work while this happened and my daughter happened to catch a little bit of it on tape. I feel so terrible for killing this beautiful Goby and of course it's so frustrating to waste money.
Fish stores will tell you whatever you want to hear so you'll buy their stuff - NEVER buy fish or corals on impulse and always do your own research or it could cost you your fish, corals, or tank!