I have a brand new tank setup and it's my first saltwater tank. 36g. After the water cycled w/ live rock and levels in order, I added 4 damsels. They've been OK for 8 days. One fish is slightly larger and aggressive. I knew I needed to remove him--he went after the smallest one today and killed it. I want to take the aggressive fish out--HOW DO I DO THIS?? It's a reef tank and he's fast and smart. Smarter than me obviously. Chasing him with a fish net didn't work.