Wood in aquariums

On thinking it over, I decided to post to the List. Neale Monks writes about
fish dying after introducing rose wood to a tank. I replied personally to
him, stating that in general, all of the members of the Rose family, which
includes apples, pears, hawthorn, etc., are safe with fish, etc.  I have
thought about this quite a while, and thought I should share these ideas:

CULTIVATED roses have a generally well-deserved reputation for needing a lot
of insecticides, as they are quite susceptible to insect damage.  Among these
various insecticides are some which are "systemic," in other words are taken
up by the plant and stored in the bark and wood.  Chewing and sucking insects
are then poisoned and killed, just by chewing or sucking juices from the rose

If the rose wood was from cultivated roses, it might well have been treated
sometime with systemic insecticides, which would make the wood extremely
toxic to fish.  I have no hard scientific "facts" to back this up, but it is
worth thinking about.  To make it more puzzling, only SOME of the fish in the
aquarium died.  Poisoning would be much more likely to kill ALL of the fish.