Well right now its just in a 40 breeder. It almost touches the front and the back of it. Im looking at getting a 200DD tank here in the future so it can really grow. The rock its on is about the size of a basketball. Just to give you a good idea on the size of it. But yeah I had to build up the rocks so it had a nice place up high for it to live. It is a light hog and love good heavy flow all around it. In the year that I have had it it has only walked around twice. And both times it done it was when I was doing a mag treatment for bryopsis (sp?). I really dont think that it liked the high mag in the tank. But I guess I got really lucky when it did walk around it didnt move very fast so I could keep a good eye on it so it wouldnt get eaten by a powerhead. After I got the mag down to normal I moved it back up to where it was and it has been there since. As for how high it is in the tank I would have to say its only about 3"-4" from the top of the water so it can get as much light as it can. And for flow I have a MP10 on one side of it and a K4 on the other end of the tank. The flow is random right were its at. I think that is the key to keeping them happy is lots of light and good very high flow.