Since my initial fish kill, I'm pretty careful of this stuff. But, you need to put it all in perspective. Remember that one inch of water over one acre is about 27,000 gallons.
My disaster was from putting a big/huge pile of green oaks down into the bowl of the dry pond when the land was first cleared. I thought that big mass of wood would make great structure when it filled. Then we quickly got a 3 inch rain and I wound up with about 6 ft of water in the bowl. Within a week, it turned black but I still stocked. They died within hours. Over a month, I added enough chlorine(not recommended) to clean a dozen olympic sized swimming pools. After a couple of weeks, I put 3 or 4 BG from the creek in a minnow bucket and put it in the pond. They died within an hour. So, I pumped it dry and the Texas summer baked everything. I've had no problems since.
I can place a recently cut piece of oak on the shoreline. Within a couple of weeks, I can move it but the sand and water under it is black with leached out tanins.
I think that if I put a freshly cut 10 ft tall oak in the water, the tanins would leach out of it and the fish would probably avoid the area. When it dissipated into the surrounding water, I personally believe that it would be weak enough to not cause a problem.
And, according to Lusk, not all soils/water interact the same.
In a small container of water, I'll bet that most fresh wood will negatively effect the water.
Now, I let even cedars dry before I add them as structure.
Why take a chance?
