wood in tank

Is it okay to put any old logs or branches from a river in my fish tank?

I have one in the tank from when I set up my tank. It was out of a river but it was only small though about 50 cm long 20 cm thick. It floated for months then snuck to the bottom of the tank. I was gutted but it still looks nice.

I want to put one in a lot bigger in this time will it be okay to do?



thank you for any help