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Re: dead SAE's

Ken Guin wrote

>Thanks to everyone who responded to my questions relating to the die off of
>my SAEs. Although I did not give a lot of details about what was going on
>my tank prior to the SAEs dying, I believe David Ozenne pretty much hit the
>nail on the head.  David pointed out that several of his SAEs died after
>pruning his plants, and that SAEs don't cope very well in O2 depleted
>Just like David, I had just completed a severe plant pruning after being
>away on vacation for three weeks (I am talking jungle here) when the SAEs
There seems to be general agreement on reduced O2 as  asignificant factor
but I am interested in the "plant pruning factor" mentioned in these 2
accounts but perhaps involoved in others as well.

The existence of aquatic plant allelopathy is well documented but I wonder
how many of us have sniffed the stems and leaves of our "prunings" such as
Hygrophila difformis and other related species (Hygrophilas and Limnophilas
especially as they belong to the "Mint" family) and noted the strong
aromatic adour. These potentially toxic substances are leached into our
tanks during pruning and it is likely that some fish are more susceptible to
the resultant toxicity than others.

 It seems likely to me that there may even be a combined effect e.g. the
poisoning damages the gills and reduces the ability to absorb O2 and
therefore the SAE's respond with behaviour resembling lack of O2 at levels
of O2 that woulsn't normally bother them.

Overall this has been a very interesting thread to me and once again
underlines the value of such a forum as this one. Perhaps out of this we may
be able to come up with some guide lines for aquatic gardeners as to such
things as which species may produce toxins when pruned, whether water
changes are necessary after pruning to reduce toxicity, whether we should
only prune say 25% of our plants in the tank at any one time etc etc


Bruce Hansen, A.N.G.F.A., Advancing Australian Aquatics.
Please visit us at http://www.ozemail.com.au/~fisher/angfa.htm