i was looking on google about shelldwellers and found this guy that set up a 125 gallon and attached pieces of slate to the back walls and put shells on there so that there would be different levels for each species of shelldwellers. i think he had about 5-6 different species in there. i think that would be really cool. i like multis, bichardis, and occelates a lot. if you go to google and type in "shell dweller fish" there will be a link that says "the ultimate shell dweller tank. thats where the 125 gallon thing is.