I have been looking for nice round rocks (River Rocks) of a good size that I can use to create a Rio Xingu biotope scape but cannot seem to find them anywhere.

While diving in malaysia, I spotted quite many suitable ones on the beaches (together with some nice driftwood). Plan to pick some up the next time I go diving. Will they be aquarium safe if I boil/soak them over a long period of time?

Also, are they any known restrictions on bringing rocks back from malaysia?