My Clownfish Are happy

[Delphinus]

I think that having a bright light directly above will help to encourage it to stay put .. they really do gravitate towards light so if they can sense that by moving one direction or another -- that this takes them away from that bright light -- that they may come back. I have mine in a focal spot between two lamps (reflectors are tilted towards each other to create that focal hotspot). If for some reason one light doesn't fire, so that there's light only on one side -- and it's more than, say, an hour or two -- that sucker goes for a walk over to the lit side. It's that fast a response. It gets to be a challenge at summertime when it's light outside earlier than the tank lights turn on ("Oh! The sun's over there now ... Ok.")

But they definitely don't seem to take well to being "boxed" in - if they can sense that they're in an enclosed space they'll likely wander upwards. At the size it's at, you might be OK, for now, since it doesn't seem to be touching the reef walls yet. However just be ready for it. If it does well for you, it will grow quickly. When I bought my ritteri it was about 5" across. It was more than 18" across within 2 or 3 months. That was three years ago! I don't know how big he is nowadays. On a good day he looks 24" though. Just huge. Biggest one I ever saw was 30" across.