I've got a bright red & green one in my 75gal reef. We put it in our 40gal a few months ago before we upgraded. It landed in the sand, then began climbing until it found a spot on the back of the glass with good water flow. It parked it and never changed locations until we upgraded the tank. We had to pry it off the glass. We put it in the new tank in the same way, and it started climbing again. This time, it ended up on the front glass, and it hasn't moved since. Lol... it's right in the middle of the glass, and all we get to see is the underside. They're interesting inhabitants unless you want a lot of action.