I added my first fish to my new saltwater aquarium about 4 weeks ago. It was a Domino Damsel. She (I'm not sure if it's male or female, but my daughter named her Dotty) made it thru the first month with only one minor issue. After the first week some tiny white spots started showing up on it and she started scratching herself on the rocks. Having had a few freshwater aquariums I kinda knew what it was so I bought some medicine from the fish store and treated her. She seems to be doing better now.
I had also bought a couple Tricolor hermit crabs for the tank when I bought the damsel. They made short work of the algae starting to grow in the rocks. They are very cool and always seem to be busy doing something.
I figured after a couple weeks I'd get Dotty a friend. The Domino Damsels are a territorial fish and can be aggressive, so I had to find something that would hold its own. My overall plan is to have just 3 (maybe 4) fish in the tank with the final one being a Maroon Clownfish. Then add a sea anemone for the clownfish and fill the rest of the tank up with corals.
The tank is 30 gallons and has about 45 pounds of live rock. The rocks take up most of the tank, but it creates a great little cave system for the fish to swim through and hide. Given my tank and my plans for its future the guy at the fish store recommended a Diadem Dottyback. That's a picture of it in my tank above. Its been in the tank for a little over a week now and seems to be doing fine. The Domino stays at the top of the tank while the Dottyback stays to the bottom. It does gets chased a little by the Domino, and I'm not sure how that will work out. We'll see.
When I bought the Dottyback, I also bought two more hermit crabs. This time I bought one Tricolor hermit and one Blue Leg hermit. As of today, there are only two alive in the tank. I found only a couple empty shells and some legs from the other two. I think the Dottyback may have gotten them. Not sure if it just ate them after they died or actually killed them.
One cool thing happened with the one hermit crab. My wife likes to collect neat shells when we go to the beach. I took a few of them and put them in the bottom of the tank to see if any of the hermit crabs would switch to a new shell. This morning I saw one of the crabs actually upgraded to one of the new, white shells. The picture on the left shows him crawling up the rock with his old shell still at the bottom. The picture above shows a close-up of his new home.