Hello Tomoko I use all different size flower pots... mostly it depends on the size of the fish , really large adult cacatuoides get a much larger easier to get into flower pot then younger smaller fish like my borelliis.... I generally start with flower pots that have a 4 inch diameter top then use larger flower pots as i find need for larger caves for larger adult fish... My kribs for example have flower pots that have at least a 7 inch opening. John ------------------------------------------------------------------------- This is the apistogramma mailing list, apisto@listbox.com. For instructions on how to subscribe or unsubscribe or get help, email apisto-request@listbox.com. apisto-digest@listbox.com also available. Web archives at http://lists.thekrib.com/apisto