Suitable caves

[D9VIN]

I am setting up a 75 gallon community and I plan to have prolly 2 pairs of apistos, I was wondering if they need the inside of their caves to be smooth? I don't really want to use flowerpots, I was hoping to use some stone, to keep it a bit more natural looking. Also, where should I position the caves, relative to height?
Also, they will most likely be cacatuoides

 

[regani]

mine seem to prefer to make their home under pieces of DW over a sandy substrate with some dried leaves scatterd around. the females often expands the little cave by digging and move quite a bit of sand in the process.
I am sure rocks will work as well as long as they have nooks large enough to form small caves and there is a substrate that the female can move around easily (ideally sand). just make sure that the rocks don't affect the pH, i.e. avoid sanstone, limestone or similar which is likely to raise your pH

 

[Tedstank]

Also keep in mind the territory requirements. When I was breeding Cacs, I had a trio of one male and 2 females and a pair of Borellis in a 55 gal. The 2 female cacs each claimed a territory of approx 1/3 of the tank at each end. The Borellis were then forced to take the middle of the tank... no real problems and no fights. It is interesting the the male cac also retired to the middle with the Borellis when the female cacs were nesting... which nwas nearly constant at one end of the tank or the other. The male cac also had reign over the whole tank except at times that the females wanted no one near the brood. It was fun and interesting to watch how they all were compatable and basically got along....once the territories were established... the more (bigger) the better.

The brood survivals were hit and miss, which didnt bother me, it wasn't my reason for having them. A few always survived and would have to be pulled out.