"john d hamilton" wrote in message
...
I have got about thirty goldfish in a plastic cold water storage tank
about 4 metres long 1metre deep and about one metre high.

It's full of sludgy mud at the bottom. normally they don't disturb the

mud and the water stays clear. lately though they have been rushing and

thrashing about and the tank water now just looks black.

I'm wondering what is the easiest way to clear out the mud at the botto
m
of the tank. my first instinct would be to take a small bucket and kee
p
spooning out the sludge. but i wondering if all the sludge got really
stirred up, and this would certainly do it; whether the fish would suff
er
discomfort, and whether their gills and breathing can filter out all th
e
mud particles, without any trouble? any suggestions to a novice most
welcome.
====================That mud can turn "sour" and start to release deadly gasses into the wate
r.