What I did when I found a peice of wood in my stream was boil it for roughly an hour (If you can-sometimes the peices are too long), then I soaked it in some vinigar (I don't think you have to soak it in vinigar. If you are happy that the wood is thoroughly clean don't bother), then I ploped it in my 50 gallon tank that houses angels, rasboras and rainbows. It has been around a month and a bit since then and every thing is fine.
And the peices look great!