I have cedar, I have fish, they are big and fat, the clubs have been to my open houses, seen the tanks, the fish and the wood.
If they are toxic, where is the real evidence?
You do not know and have no personal experience either.
Why should folks listen to that?
I mean....... really???
So do a google search:
They suggest that the leachates are moderately toxic, but this is fresh live wood, not old well leached wood. I could say this for most any fresh live wood. So the age and soaking of the wood makes a large difference, water changes, use of activated carbon etc.
This adds a lot more to the discussion and applied issues aquarist have....
Will ADA As leach ammonia 1 years from now?
Same type of thing here, is it fresh, do you do water changes, do plants take it up, do bacteria break it down, does it matter to fish?
As with ANY toxicant, dose makes the poison.
This means concentration X exposure.
If the concentration is extremely low, and is diluted frequently, there's a lot of other bacteria, pH is not reduced, the wood itself is well soaks and aged prior to use, not fresh wood etc.........you use carbon etc..........
This really becomes a non issue.
If you plan on going out and chopping fresh cedar, adding lots to an aquarium, don't do water changes or use carbon......well yea, but that can be said for most all wood............
How you apply the info and process it is far more important than the info itself.