Weeping Willow, will it kill my fish?!

[willow66]

I have been told that if the leaves of a Weeping Willow fall into my pond they are toxic and will kill the fish. Does anybody know if this is true?

[hammerman]

The leaves of any tree can prove dangerous to a pond....but only if the pond is allowed to freeze over.

As the leaves sit at the bottom, they decay and rot giving off gasses which can get trapped under the ice. By floating a tennis ball on the pond or leaving any filters or pumps going, a small hole can be left where the gas exchange can be made.

Willows are no different although their leaves contain salicic acid (stuff that asprin is made from). I would be more worried about the roots getting into the pond....willows love water and will seek it out from vast distances.